Military Historical Library

Chapter 5. Combat Operations by the Sides during the Course of Negotiations for a Ceasefire [1]

Per the proposal of the USSR representative to the UN and the Security Council on 10 July 1951 representatives of the Supreme High Command of the Korean Peoples Army and the Chinese Volunteers and representatives of the American command began negotiations for a ceasefire in the city of Kaysen .

The relationship between the ground forces at this time was relatively even. The forces of both sides had gone over to the defensive, and the war in

Korea

had taken up a positional nature. In this the forces of the CPV and KPA went over to the defense with the goal of maintaining a solid hold on their positions at the front and repulsing any possible landings on their coasts. The UN forces as well as the South Korean army, other than the domination of their fleet of the waters of Korea , were only defending along the front line.

When the negotiations began the front, beside the area of Kaysen, was 10-55 kilometers north of the 38^th Parallel along the line Yoson River Delta – south of Kaysen – Suuk – Chorwon – Kumhwa – Konkol’ – Yimonchijon – Matsadin.

The force grouping of troops of the Chinese Volunteers and the Peoples Army was as follows.

In the western and central sectors of the front and running along an overall distance of 130 kilometers were the defenses of the CPV. The 19^th CPV Army with four corps (47^th, 63^rd, 64^th and 65^th) defended an 80 kilometer line from the Yoson River delta to Chorwon. The line from Chorwon to the Bukhan River covered 50 kilometers and was defended by the 9^th CPV Army with three corps (20^th, 26^th and 27^th). The operational structure of the armies was in two echelons.

The army corps, which each had three divisions, were defending as follows: the 64^th CPV Corps defended from the Yoson River Delta to Suuk. Combat order of this corps was in a single echelon. The zone from Suuk to Haktori was defended by the 47^th CPV Corps. Combat order of this corps was structured in two echelons: one division formed the first echelon, and two divisions formed its second echelon. In the zone from Orichon to Gaysonri was the 63^rd CPV Corps with its combat order structured in three echelons. The zone from Pyongkan to Kumhwa was defended by the 26^th CPV Corps. Combat order of this corps was structured in two echelons. The line Hasori – Maetol’bau was held by the 20^th CPV Corps with its combat order in a single echelon. At the seam between the 19^th CPV Army and the 9^th CPV Army and somewhat behind it along the line Tesudon – Sangapni – Chongdon was the 42^nd CPV Corps of the 13^th CPV Army defending in two echelons; this corps was now directly subordinate to the Unified Command. The width of the zones defended by the corps depended on their mission, their makeup and the nature of the terrain and varied from 15 to 55 kilometers.

The 65^th CPV Corps of the 19^th CPV Army and the 27^th CPV Corps of the 9^th CPV Army were held in the second echelon of their respective armies and situated with the former being in the area west of Singae and the latter being in the area of Chingdori.

The 1^st KPA Army, consisting of the 8^th, 19^th and 47^th KPA Infantry Divisions, was deployed along the Ahyonni – Hokuni – Teondon line in order to defend the Yenan area and support the right flank of the 19^th CPV Army.

The line from the Bukhan River to the seacoast was defended by the forces of the 5^th, 2^nd and 3^rd KPA Armies. The 5^th KPA Army (the 6^th, 12^th and 32^nd KPA Infantry Divisions) defended the line Sonumoku – Konkol’. To its left, along the line of the pass north of Imdamni – Jingoge – Siaehiri – Sangol, the 2^nd KPA Army (the 2^nd,13^th and 28^th KPA Infantry Divisions was defending. These armies had two divisions in their first echelon and one in their second. The zone from Sangol to Matsadyan was defended by the 15^th KPA Infantry Division of the 3^rd KPA Army. Two divisions of this army (the 45^th and 1^st KPA Infantry Divisions) defended along the coast in the sectors at Koson and Paetchen. The width of the zones defended by the KPA armies varied from 20-30 kilometers.

For that reason, along the 200 kilometers of the front there were 36 infantry divisions defending, of which 24 were CPV and 12 were KPA, and of these 18 divisions were in the first echelon, four supported the flanks, and the rest were in the second and third echelons of the army corps and second echelon of the armies. The average density saw one infantry division covering 6 kilometers.[2]

The densest grouping of forces and means was in the center on the front from Suuk to the Bukhan River . The average operational density in this sector was one division per 3.8 kilometers of front.

The west coast, stretching more than 500 kilometers from Yenampo to Haeju was defended by the forces of the 4^th and 6^th KPA Armies and the 13^th CPV Army.

The 4^th KPA Army, consisting of the 4^th, 5^th and 10^th KPA Infantry Divisions, the 105^th Mechanized Division and the 26^th KPA Marine Brigade, defended the area from Anju to Nampo on a front of 140 kilometers. Only the 26^th KPA Marine Brigade was directly responsible for coastal defense, and the rest of the forces were concentrated 20-25 kilometers inland in readiness to move to launch a counterstrike against an enemy naval landing at any point along the coast. The 10^th KPA Infantry Division was concentrated in the area of Undaen, the 105^th Mechanized Division was concentrated north and south of Sukchen, the 4^th KPA Infantry Division was in the area of Kiyanri, and the 5^th KPA Infantry Division was in the area southwest of Tintiri.

The 6^th KPA Army, consisting of the 9^th and 18^th KPA Infantry Divisions, the 17^th Mechanized Division, and the 23^rd KPA Marine Brigade, defended the coastline from Nampo to Haeju on a front of 250 kilometers. Only the 26^th KPA Marine Brigade was directly responsible for coastal defense, and the rest of the forces were concentrated 30-80 kilometers inland in readiness to move to launch a counterstrike against an enemy naval landing at any point along the western and southern directions. The 18^th KPA Infantry Division was concentrated southwest of Synhori, the 17^th Mechanized Division was in the area of Sariwon, and the 9^th KPA Infantry Division in the area west of Techunin.

The 13^th CPV Army, consisting of four corps, was using its own 50^th CPV Corps, to defend the coast from Yenampo to Anju (a front of 130 kilometers), and the rest of the corps were in readiness to launch counterstrikes: the 38^th and 39^th CPV Corps were in the zone of the 4^th KPA Army and the 40^th CPV Corps was in the zone of the 6^th KPA Army. The corps were concentrated along 50-70 kilometers from the coast in the following areas: the 38^th CPV Corps – in the Sunchon area; the 39^th CPV Corps – north of Sonchon; and the 40^th CPV Corps – in the Fanju area.

Overall the defense of the west coast along the front from Yenampo to Haeju saw 17 deployed infantry divisions, 2 mechanized divisions, and 2 marine brigades. The average operational density was 25 kilometers per division.[3] The most densely defended force grouping of troops and means were in the Tonju and Nampo sectors. Average operational density here was 12.5 kilometers per division.

The east coast ran from Paetchen to Chengjin and covered nearly 500 kilometers which was defended by the 7^th KPA Army, consisting of four infantry divisions and two marine brigades. The main body of the army (three divisions and one brigade) were concentrated in the Wonsan area and deployed as follows: the 3^rd KPA Infantry Division – the Anbien area; the 37^th KPA Infantry Division – west of Sokken; and the 7^th KPA Infantry Division – in the Mantszanni area. The 46^th KPA Infantry Division was located in the Hamhyn area, and the 24^th and 63^rd KPA Marine Brigades were defending directly on the coastline with the former in the Wonsan area and the latter northeast of Hamhyn.[4] The 20^th CPV Army with the 67^th and 68^th CPV Corps was concentrated in the areas of Yandok, Tonyan, and Kocha, kept in readiness to launch counterstrikes on any enemy naval landings in the Wonsan area.

Overall, coastal defense was allocated 10 infantry divisions and two marine brigades. The average operational density was around 45 kilometers per division.[5] The heaviest density of force groupings of troops and means were in the Wonsan area along the Hekkok – Munchen front. Average operational density in this sector was one division per 5 kilometers.

In reserve the Unified Command had the 3^rd CPV Army (the 12^th, 15^th and 60^th CPV Corps) which was concentrated in the Koksan, Namden and Karechu areas.

Overall there were 72 infantry divisions, 2 mechanized divisions, 4 marine brigades (of which 51 infantry divisions were CPV and 23 divisions and 4 marine brigades were KPA), 3 howitzer artillery divisions, 1 rocket artillery division, 2 antitank artillery divisions, 4 antiaircraft artillery divisions, an independent howitzer artillery regiment, an independent mortar regiment, 3 antiaircraft artillery regiments [6], 11 engineer and engineer-sapper regiments, 3 antiaircraft artillery battalions, and 2 independent tank companies.

The average size of a Chinese Volunteer division was 10,500 men, and those of the Peoples Army were 9,037 men.

The CPV and KPA air forces operated as part of the Unified Air Army (OVA) which included 6 fighter, 3 ground attack, 2 bomber and 1 combination aviation divisions, with a total number of 588 aircraft. The air army was based at airfields in the areas of Antung, Sinuiju , and the Supung hydroelectric power station, and was given the mission of covering important objects in the rear area.

The DPRK Navy did not have any warships and was only able to provide coastal mine-laying activities.

For that reason, the force grouping of CPV and KPA forces was created with the necessity to ensure that it could solidly hold the line immediately adjacent to the front and repulse any enemy landings on the coast.

The overall size and weapons quantities held by the CPV and KPA forces is shown in Table 14.

The artillery units and subunits of the CPV and KPA were still facing a shortage of fire control equipment, and their personnel were still poorly trained in conducting fire under mountainous conditions. The tankers did not have a great deal of driving skills and knowledge of how to correctly operate their vehicles. Engine resources hours on many of the tanks and self-propelled guns were expended. Spare parts for repairs of tanks were not available. Repair units were not able to guarantee the timely and quality repair of vehicles. In the air forces the KPA forces only had 60 well-trained crews[7], which did not permit them to make full use of their available air park. Beside that, the CPV and KPA air forces suffered from a dangerous shortage of spare parts with the consequence that a significant portion of their aircraft was non-operational. Supplying the CPV and KPA with all types of goods was frequently not carried out in a timely manner due to the lack of a sufficient number of trucks and the effects of enemy aviation on their access routes.

Against the CPV and KPA forces stood the 8^th US Army consisting of the I, IX and X US Corps and the I ROK Corps.

I US Corps consisted of the 1^st Cavalry, 3^rd and 25^th US Infantry Divisions, the 1^st and 9^th ROK Infantry Divisions, the 28^th and 29^th British Infantry Brigades, the 25^th Canadian Infantry Brigade, and the independent Turkish Infantry Brigade, with one division in reserve to defend the zone from the delta of the Imjin River to Kumhwa. The zone from Kumhwa to the Buhang River was defended by the IX US Corps with the 7^th and 24^th US Infantry Divisions and the 2^nd and 6^th ROK Infantry Divisions. All of these divisions were placed in a single echelon. The zone from the Buhang River to Uimonjong was defended by the X US Corps, consisting of the 1^st Marine Division, the 2^nd US Infantry Division, and the 5^th, 7^th and 8^th ROK Infantry Divisions with one division in reserve. The I ROK Corps with the 3^rd, 11^th and Capital Infantry Divisions was defending the zone from Uimonjong to the coast. The combat order of this corps was in a single echelon. The width of the zones for each corps varied from 30 to 100 kilometers. Beside that, the UN forces had a number of independent regiment and battalion of ROK Marines and two detachments of South Korean coastal defense forces, an independent Thai infantry regiment and four independent infantry battalions (French, Dutch, Greek and Filipino) directly on the front lines.

In their reserves the American and South Korean command had 10 independent infantry regiments, 11 independent infantry and security battalions, and 5 coastal defense detachments from the South Korean forces, whereas the Americans had an airborne regiment and Ethiopian and Colombian infantry battalions.

Overall in Korea they deployed 16 infantry divisions, one marine division (of which 7 were American and 10 were South Korean), 4 infantry brigades, 11 independent infantry, 2 independent tank, and 2 independent field artillery regiments, an airborne regiment, an independent marine regiment, 17 independent infantry and security battalions, an independent marine battalion, 3 independent tank battalions, 18 independent field artillery battalions, 9 independent antiaircraft artillery battalions, and 7 independent coastal security detachments.

The average strength of the American divisions was 16,000 men whereas the South Korean divisions numbered 10,180 men.[8] The average operational density was 8 kilometers per division.[9] The densest force grouping of forces and means was in the center along the Chorwon – Buhang River front, where the density in this sector approached one division per 6 kilometers of front.[10]

For replacements for those divisions operating at the front the South Korean command had a territorial army, “Protectors of the Motherland,” in which they had one corps headquarters, seven reserve divisions, and one reserve regiments.

For that reason, the entire UN forces and South Korean army were able to deploy immediately to the front with the American divisions defending those directions where they were best able to use the might of their military technology. The South Koreans had their forces operating in the intervals between the American divisions and on the most inaccessible terrain.

As well as the 5^th Air Army tactical aviation, they also deployed three strategic bombing wings, a Marine Air Wing, as well as aircraft carriers and land-based aviation. Overall the UN air forces numbered 1,595 aircraft. Their aviation carried out immediate support for the ground forces, as well as destruction and disruption of industrial centers, settlements, airfields and lines of communication.

The UN naval forces and the South Korean army numbered 180 warships and more than 120 naval auxiliaries, landing ships and transports. They carried out the mission of blockading the DPRK from the sea, carried out systematic bombardment of ports, settlements and other objects close to the coast, as well as provide fire support for ground forces operating in the coastal areas of the front. These tasks were carried out by the ships of the fleet, as is correct, in cooperation with carrier aviation.

The size and numerical elements of the American and South Korean armies are shown in Table 15.

*Note – does not take into consideration transports and of this number 675 aircraft are fighters or fighter-bombers.

For that reason, the overall superiority in personnel, artillery and mortars was on the side of the Chinese Volunteers and Peoples Army, but tanks and aircraft were in the favor of the UN forces and the South Korean army.

But at the same time the correlation of forces immediately at the front in personnel, artillery and mortars was about even, but tanks and aircraft were more favorable to the American side, as a significant part of the CPV and KPA forces and means (29 infantry divisions and 4 brigades with their reinforcing means) were allocated for defense of the east and west coasts, and their aviation carried out covering important objects in the rear area.

Drawn into the negotiations for a ceasefire in Korea , the ruling circles in the USA did not want to strive to quickly terminate the way the war had developed for them and proposed to use all efforts to break off these negotiations. With this goal in mind the American representatives put forth unacceptable demands. They called for the establishment of a demarcation line and the creation of a demilitarized zone that stretched deep into the rear of the positions of the Chinese Volunteers and Peoples Army, which would cover more than 13,000 square kilometers of the territory of the DPRK (see figure 4.)

The Americans representatives called for the right for control over the rear area of the Chinese Volunteers and the Peoples Army, e.g. they were striving to use the negotiations to interfere with the internal affairs of the DPRK.

Along with this the Americans continued to make systematic attempts to provoke military incidents in the neutral zone in the Kaysen (Kaesong) area and by that means create unacceptable conditions for the work of the Sino-Korean delegation, which made the conduct of negotiations nearly impossible. As a result negotiations broke off on 23 August.

From the very beginning of negotiations and with the goal of putting pressure on the Sino-Korean side, the Americans likewise interfered with the latter by refusing to offer a ceasefire through the aggressive operations of their forces.

Beginning in July 1951 the Americans gradually rebased the majority of their aviation (except for their B-29 strategic heavy bombers and fighter reserves) from Japan to airfields in South Korea and sharply increased their aerial bombardment of troops and especially objects in the rear areas of the CPV and KPA. Every day the Americans carried out up to 700 sorties.

Simultaneously the UN forces increased naval bombardments of settlements, lines of communication and other objects on the west and east coasts as well as the active operations of their forces directly at the front.

On 18 August the enemy went over to the offensive on the eastern sector of the front against the forces of the 5^th, 2^nd and 3^rd KPA Armies with the forces of eight divisions (the 2^nd US Infantry Division, the 1^st Marine Division, and the 3^rd, 5^th, 7^th, 8^th, 11^th, and the Capital ROK Infantry Divisions) with the support of naval artillery and with the goal of moving the front lines to the north and by that in and of itself put into effect the unfounded demands of the American delegation to the conference in Kaysen (Kaesong) on establishing the line of demarcation somewhat north of the 38^th Parallel and in the rear of the positions of the CPV and KPA. (See Figure 5).

The enemy advanced on the entire front with independent reinforced regiments and battalions and but no single strong force grouping of forces and means was sent on any single direction. Divisions, as is correct, operated in zones of 8-10 kilometers. During the course of the offensive KPA strong points and nodes of resistance were sequentially suppressed by artillery fire and air strikes, after which they were taken by infantry subunits. The offensive developed slowly, took on an indecisive nature and was primarily carried out by troop movement in straight lines. The enemy moved only 1-5 kilometers to the north over the course of several days.

To stop the offensive, the forces of the 5^th, 2^nd and 3^rd KPA Armies went over to the offensive on 26 August and threw back the enemy in a number of sectors, moving up to 5 kilometers into the depth of the enemy defenses. The enemy launched numerous counterattacks against the KPA forces wedging their way in and during the course of violent battles forced them back to their starting positions by 2 September.

With the breakdown of the offensive in the eastern sector of the front, the enemy turned to the western sector for active operations at the end of September, and then to the central sector of the front. On 25 September 8^th US Army commander General Van Fleet reported the beginning of the fall UN and South Korean army offensive. In planning this offensive, the enemy went for the same goals he had during the summer offensive.

On 3 October three enemy divisions (the 1^st British, 1^st Cavalry, and 3^rd US Infantry) went over to the offensive against the forces of the 64^th, 47^th and 42^nd CPV Armies in the Manjan- Chorwon sector (see Figure 6.)[11] The divisions advanced in zones of up to 10 and more kilometers and had the mission of taking important individual tactical heights in the CPV defenses.

The enemy succeeded in seizing several heights and settlements in the defenses of the Chinese Volunteers, but at the same time, eventually running into stiff opposition and taking heavy losses, they were forced to break off the offensive on 8 October. The greatest depths achieved by UN forces in this sector were 4-5 kilometers.

On 13 October, enemy forces consisting of four infantry divisions (24^th and 7^th US and 2^nd and 6^th ROK), with 200 tanks and massive air support, went over to the offensive in the Kumhwa – Bukhan River sector against the forces of the 67^th CPV Corps of the 20^th CPV Army. (See Figure 7)

The offensive in this sector was carried out by reinforced regiments and battalions on individual directions. During the course of the offensive the enemy strove to take Chinese Volunteer strong points with a goal of taking them from the flank or rear.

The battles took on a terrible nature. The enemy, using their superiority in aviation and tanks, had reached Kimsong by 20 October, wedging up to 10 kilometers into the CPV defenses. Ultimately their attempts to break through to the north were stopped by the CPV units.

For that reason, following the breakdown of the summer offensive by the UN armed forces was the failure of their so-called fall offensive. During the enemy offensive the CPV forces, artfully making use of the conditions of mountainous terrain, took the enemy units and subunits from the flanks by skillfully counterattacking him. In a case where the enemy had a superiority of forces and there was no way that their positions could be held any further, the CPV forces would withdraw, simultaneously preparing their forces for a counterattack. The counterattacking units normally had the mission of destroying the penetrating enemy and restoring their positions. When the counterattack was unsuccessful, they would repeat it several more times and continue until that point in time when the enemy was either destroyed or their own forces had suffered such losses that further operations were impossible.

With the breakdown of their summer and fall offensives, the UN returned to the negotiations for a ceasefire once again. On 25 October 1951 the delegations of both sides carried out their first meeting since the breakdown in talks. They jointly decided to move the talks from Kaysen ( Kaesong ) to Panmunjong (Hammontaen) which was located close to Kaysen.

On 27 November 1951 an agreement was reached on the demarcation line, which was then established based on the current lines held by the opposing forces of the sides, and in early 1952 an agreement was reached on all of the points put forth with the exception of the exchange of prisoners of war.

According to the conditions of the agreement the established demarcation line would not change if the ceasefire was signed within 30 days. If the agreement for the ceasefire was not signed in that period of time, then after the achievement of a ceasefire on all other points the demarcation line and the demilitarized zone would undergo the necessary changes in accordance with the operational lines of the opposing forces.

By 27 November 1951, the lines of the opposing forces covered 225 kilometers and basically followed the 38^th Parallel from the delta of the Han River – Panmunjong – Orichon – Hasori – south of Kimsong – south of Baugol – Chansong – Phoyedin. This line was held with insignificant changes through the end of the war.

At the moment of the conclusion of the agreement on the demarcation line, the force grouping of troops of the sides were in the following locations.

Along the line from the delta of the Yaesong River to Chunsimpo, a distance of 170 kilometers, the CPV forces were defending. The 19^th CPV Army (42^nd, 47^th. 63, 64^th, and 65^th CPV Corps) were in a single echelon operational formation defending 100 kilometers of the line from the delta of the Yaesong River to Wolchon. The 20^th CPV Army (12^th, 26^th, 67^th and 68^th CPV Corps) was in a two-echelon operational formation, defending the 70 kilometers from Wolchon to Chunsimpo. The second echelon army – the 67^th CPV Corps – was concentrated in the area of Saepori. The corps were defending positions 12 to 33 kilometers in width, and they maintained their combat order in two echelons.

The line from Chunsimpo to the east coast was 55 kilometers wide and was held by the forces of the 2^nd and 3^rd Korean Peoples Army Armies, deployed in an operational formation of two echelons, and defending zones of up to 15 kilometers wide. The 6^th KPA Army had one division directly on the front line, which was defending a zone 25 kilometers wide. Two infantry divisions of this army (the 9^th and 18^th KPA Infantry Divisions) were defending the coast from Koson to Paetchen.

Overall there were 36 divisions deployed (27 Chinese and 9 Korean) of which 20 were in the first echelon, and the rest were in the second echelons of the corps and armies.[12] The average operational density was 6.6 kilometers per division.[13]

The west coast from Yenampo to the delta of the Yaesong River was defended by the forces of the 4^th and 1^st KPA Armies, the 105^th Mechanized Division, and the 10^th KPA Infantry Division, the 13^th CPV Army and the 50^th CPV Corps – a total of 17 divisions and two machine gun artillery brigades.[14] The main force grouping (13 divisions and one brigade) remained as before in the sector from Anju – Nampo.

The east coast from Paetchen to Pukchyon was defended by the forces of the 7^th and 5^th KPA Armies, the 46^th KPA Infantry Division, and the 24^th and 25^th KPA Machine Gun Artillery Brigades, as well as the 9^th CPV Army and 47^th CPV Infantry Division – a total of 14 divisions and two brigades. All of these forces with the exception of one machine gun artillery brigade were located in the Paetchen – Hamhin sector.

Overall the coastal defenses on the east and west coasts were allocated 31 divisions and four machine gun artillery brigades.

In reserve the Unified Command had the 3^rd CPV Army (15^th and 60^th CPV Corps) which were concentrated south of Koksan.

These force groupings were retained to the end of the war. They were maintained by the primary method of replacing one formation with another.

Overall, on 27 November 1951 there were 75 divisions and 4 brigades located in

Korea

, e.g. one division more than there was at the beginning of negotiations.[15]

For closer cooperation between CPV and KPA forces, in early October 1951 a unified command of forces was created on the western and eastern coasts who had all forces carrying out coastal defense missions subordinated to them.[16]

As before, the CPV and KPA forces were opposed by the I, IX and X US Corps and the I ROK Corps of the 8^th US Army.

I US Corps (the 1^st US Cavalry Division and 3^rd US Infantry Division, the 1^st British Division, the 1^st and 9^th ROK Infantry Divisions, and the Turkish Infantry Brigade) were defending a 90 kilometer zone from the Han River delta to Wolchon. From Wolchon to the Bukhan River a 55 kilometer zone was defended by the forces of IX US Corps (the 2^nd, 24^th and 25^th US Infantry Divisions, and the 2^nd and 6^th ROK Infantry Divisions). The zone from the Bukhan River to Sachenni, stretching 50 kilometers, was defended by the X US Corps (1^st Marine Division, 7^th US Infantry Division, and 3^rd, 7^th and 8^th ROK Infantry Divisions) and from Sachenni to the coastal area the 25 kilometer wide zone was defended by I ROK Corps (5^th, 11^th and Capital ROK Infantry Divisions.) All corps kept one infantry division in reserve.

Overall the enemy maintained 18 divisions, 1 brigade, 1 independent regiment, and 19 independent battalions at the front, with 14 divisions and 1 brigade in their first echelon and 4 divisions in the second echelon. In reserve, the Americans and South Koreans had one regiment and 19 battalions. The overall correlation of forces by 27 November 1951, not considering losses taken from August-October 1951, was nearly unchanged.

After the establishment of the front demarcation line, things remained primarily stabilized. Combat took on a localized nature, and was fought with a goal of reconnaissance and seizing individual strong points and heights.

To improve their positions, starting in November 1951 the CPV and KPA forces began to excavate underground shelters.[17]

The underground shelters initially were made as small cul-de-sacs which could be excavated by a squad or platoon – the platoon version was designated as the primary model for protecting personnel and combat technology from artillery fire and air strikes.

By the end of 1951 the CPV and KPA forces immediately at the front had two defensive lines: the first – along the forward edge of the defense where the forces were in contact and reaching back to a depth of 5-12 kilometers, and the second – 10-40 kilometers behind the first line of contact along the line Tamimen – Ichen-men – Saepori – Hwachenni with a depth of 2-4 kilometers (see Figure 8.) The basic form of the defense was a system of strong points, which in the second line of defense were only set up to defend individual sectors.

On the west coast two defensive lines were also set up in order to repulse possible enemy assault landings: the first one ran from the delta of the Chongchon River along the seacoast to Nampo with a depth of 10 kilometers, and the second one ran from the forward edge of the defense along the line Sunan – Pyongyang – Fanchu. From Nampo along the seacoast to Haeju and from the delta of the Chongchon River to Tel’san individual strong points were set up along the directions from which it was most likely the enemy would land. Beside that, defensive works were built along the line Haeju – Chonsoktu.

Along the east coast, engineer works were concentrated for the most part in the areas of Wonsan and Hamhung – the points of possible enemy assault landings. In these areas a complete system of strong points extending to a depth of 15-20 kilometers was constructed.

The tasks for defending forces were established based on possible enemy operations. The operational plan of the forces included the following. In case of an offensive by the enemy against the front of a first-echelon CPV corps as well as the 2^nd, 3^rd or 1^st KPA Armies, they would strongly defend their positions and inflict as heavy losses as possible on the enemy. If the enemy created a wedge in the defenses, it was planned to use the 38^th or 40^th CPV Corps on the directions of Chunfa – Namchyon; the 15^th and 60^th CPV Corps if along the direction Inchen-Men, but further use would be based upon the situation – either on the central sector of the front or on its left wing; the 20^th CPV Corps was to be used along the railway to Pyongkan; the 67^th CPV Corps on the direction of Kimsong.

In case of a major assault landing in the areas of Nampo and Wonsan , and with insignificant activity by the enemy along the front, the first echelon corps as well as the 2^nd, 3^rd and 1^st KPA Armies would take every measure to ensure the enemy was repulsed before he wedge into the defenses. The 15^th and 60^th CPV Corps, moving in the direction of Fanchu, would be used to reinforce the force grouping of troops on the west coast and work with them to destroy the enemy west of the line Anju – Pyongyang – Chunfa. The troops deployed on the east coast would take up strong defensive positions until the situation on the west coast became clear, and then choose the right moment to inflict a counterstrike on the enemy.

And finally, if the enemy made a major assault landing on the west coast with a simultaneous offensive along the front, but only conducted demonstration operations against the east coast, then the forces would operate using the second option. Beside that, the forces on the west coast would be reinforced by one corps from the east coast.

For that reason, the operational plan of the CPV and KPA forces was based on a strong defense of the occupied line with reinforcement along the threatened directions by use of second echelon corps and reserves, which would fully respond to the situation created.

Having not achieved any measurable successes in their summer and fall 1951 offensives, in January 1952 the American forces began a systematic and massive aerial bombardment of objects in the rear area having either military or economic significance, areas where troops were deployed, lines of communication, and even peaceful settlements.[18] Along with these actions American forces, violating all international norms for the conduct of war, began to use bacteriological warfare and chemical weapons in January 1952, weapons whose use was forbidden by international convention.

From materials from the international commission on the examination of the facts of the conduct of bacteriological warfare it follows that the Americans used bacteriological weapons in Korea from 28 January to 24 April 1952 over a total coverage of 347,000 square kilometers, and against northeastern China from 29 February to 4 April 1952, covering a total area of around 780,000 square kilometers.

The bacteriological strikes were launched against individual CPV and KPA troop positions, frequently against objects in the rear area, lines of communication, railway junctions and dirt roads, some industrial and agricultural areas, ports and in some isolated cases reservoirs. The main method of use of bacteriological weapons both in Korea as well as in China was to spread illness-causing microbes (pathogenic plague, Asiatic cholera, Siberian flu, peritoneal typhus, etc.) via live carrier agents (flies, fleas, spiders) and to a lesser degree via dropped objects (feathers, leaflets and others). The live carrier agents and all possible objects, saturated with illness-causing microbes, were dropped in bacteriological bombs and containers for which the primary vehicles for delivery were the B-26 and B-29 bombers.

When using bacteriological weapons aviation was used in either single aircraft or group raids. The largest number of aircraft used in a single raid was no more than 16. The bacteriological bombs and containers were dropped in horizontal flight, at low altitude, and on occasion from a dive. With a goal of masking the use of bacteriological weapons they were dropped, as is correct, at night, in fog, in cloudy or rainy weather, and in concert with the use of high explosive bombs. Beside that, barrier mists were produced by the Americans by means of spraying directly from the aircraft via the use of aerial devices designed for this purpose.

The combat effectiveness of the use of bacteriological weapons was insignificant. This is clarified first and foremost by the fact that they were not used in a massed nature, and the means of use by themselves were ineffective. The undertaking of attempts to use bacteriological means by the Americans, perhaps, was only a very limited mission and presented itself as an insignificant experiment, directed at the study of individual questions related to the use of carriers of illness-causing microbes.

With the beginning of the use of bacteriological weapons against the DPRK and PRC there were widely used sanitary-prophylactic measures taken with the goal of preventing the possibility of contracting these diseases, and anti-epidemic measures focused on the immediate elimination of the consequences of the use of bacteriological weapons.

Combat operations along the front took on a localized nature, and both sides tried to seize individual strong points and heights. At the same time both sides undertook operations to improve their defenses.

The CPV and KPA forces, assured of the fact that the underground bunkers they had created were reliable protection against any means of destruction, began to expand their fighting works. Small cul-de-sac underground approaches for squad-platoon level formations, which previously only served to protect the troops from artillery fire, began to be expanded in early 1952 to form galleries designed to provide concealed underground approaches with access to the underground bunkers and places for situating combat technology. These galleries could also be used to place fire on an advancing enemy.

The galleries were limited to platoon-company size units and were used for the most part along the front lines and only occasionally in the depths of the defense. They reliably protected troops and combat technology from air and artillery strikes, permitted commensurate use of maneuver under conditions of intensive artillery and aviation bombardment, and finally provided communications between firing works deployed along the front edge of the battle area and the rear area. The galleries were considered as part of the trench line and pathways which provided the highest degree of survivability and steadfast defense.

The first time galleries were employed was done in an artless fashion. The troops concentrated in the galleries for protection from enemy fire, and the trenches and connecting paths were not further developed, and often they were not occupied by the troops. Under these conditions there was no way to provide fire from underground works to cover all approaches to the defense. They did not support the use of multilayered fires and sharply reduced observation of the battlefield. Subunits were thus isolated from each other, lacked communications between them, and most of their fire support assets could not be used on the forward edge of the defense. As a result defense of the forward edge of the defense became passive in nature. Subunits were located in the galleries, could only carry out fire from a limited number of means, and when entrenched in this manner could not organize counterattacks with the second echelon or reserves.

The first time galleries were used it was not according to plan, but per the initiative of the subunits. Planned combat in connection with these works corresponded to the ability to use previously built galleries. This led to the fact that engineer works dominated the terrain, and combat operations were soon planned around their use.

Beside that, underground works were primarily built on the tops of the heights, which led to an increase in the “dead zones” and contradicted the requirements to base the disposition of the engineer works for the tactical value of the use of fire support assets.

In May 1952 the Unified Command demanded that the troops create more steadfast defense by means of developing and improving field type defensive works and construction of permanent works along the individually most important directions. All was ordered for the commensurately improved engineer works to be placed among the order of the first echelon divisions; in individual sectors they were rebuilt and for that reason an amalgamation of the second defensive line (second-echelon divisions of the corps and Korean armies) with its forward edge along the line Kaysen – Wicholli – Anhyob – Mundori – Imdanni – Changdori – Soguchyon – Hill 1098; the second echelon armies and reserves created an amalgamated third line of defense with its forward edge along the line Sariwon – Sohing – Ichen-Men – Saepori – Hwachaenni; additionally, reinforced concrete defensive works were built in the areas of Sohing – Namchyon – Nuchyon; as well as field defensive works were built along in the most important locations, in the areas of Anju, Kongso, and Sinkosan individual reinforced concrete defensive works were also constructed.

The primary works used to equip these defensive lines were of the underground type, which had to be use to form the backbone of a strengthened defense. The construction of permanent defensive works (DOS) was allocated to the areas of Sariwon, Sibili, Tozan, Saepori, Changdori, Mal’hiri and Mazanni.

The overall depth of the defensive belts immediately along the front was 30-50 kilometers. The work listed above was mostly completed during 1952.

The UN forces at this time were preparing the “Ermine” defensive belt with its forward edge along the line of contact with the CPV and KPA forces, intermediate positions along line “Wyoming” with the forward edge of that line running from Chochanni – Chihotey – Sabangori – the Bukhan River, and defensive belt “Kansas” with its forward edge along the line of the Imjin River delta – Tosiri – Chongdok – the south bank of the Hantanchyon River to Unchon – Hantuso – Simpori – Hwachen – Tonzuri – Dayam Mountain – Hill 1078 – Chaedin.

The first defensive line, “Ermine”, and the intermediate positions along “ Wyoming ”, were defended by the first echelon divisions of the corps, but those in zone “ Kansas ” were defended by divisions of the second echelon of the corps.

The basis for all defensive lines was the strong point and nodes of resistance, covered by various engineer barriers. The enemy paid particular attention to these defensive areas: Munsan, Tosiri, Hasyuri; Yonchong, Hill 832, Jyun-Byon Peak; Chorwon; Simpori, Hwachen, Kojiori; Hudon, Sanjugol’ni; Sohori; Yimonjon, Sachenni, Hill 1078. Searchlights were installed along the main directions. The overall depth of the defenses ran from 15-45 kilometers.

Beside these indicated defensive belts, the enemy had other prepared defensive lines to defend along Suwon – Inchon – Yoju – Wonju – Masan, Taegu, Kenju (along the line of the former Pusan bridgehead.) The first of these were built in early 1951 and were considered to be the army defensive line; the second one was built even back in 1950 and was the army rear area defensive line. Both lines were not occupied by troops, and engineer work along these lines was not continued.

For that reason, the enemy paid most of his attention to holding the first two defensive belts and their intermediary positions, which is where the 8^th US Army correspondingly concentrated its strength.

At the conference at Panmunjon the American side as before carried out a policy of dragging out negotiations and breaking off the talks. To this end they used the question of repatriation of prisoners of war, which remained the only unsolved question to the achievement of a ceasefire.

In spite of all international agreements the American side openly refused to repatriate all of the prisoners of war in their hands on a one for one exchange basis. Such maneuvers by the American command was an attempt to liberate all of their prisoners of war and at the same time hold a significant part of the North Korean and Chinese prisoners of war on their side after the agreement was signed for use for their own purposes.

This demand by the American representatives was turned down by the Sino-Korean side. Then the American side declared that the CPV and KPA prisoners of war did not want to return to their motherland, and instead put forth the demand for what they called “voluntary repatriation.” But at the same time, assured that the Sino-Korean side would not accept this principle for solving the problem of repatriation, on 8 October 1952 representatives of the American command demonstratively cut off meetings and for that reason once again broke off negotiations.

After this breakdown of negotiations, on 14 October 1952 the UN and South Korean forces went over to the offensive in the area of Kumhwa. In using the offensive, the enemy side strove to seize positions held by the Chinese Volunteers on the heights north of Kumhwa and for that reason eliminate a bulge that thrust into their defenses, laying out the gallery system of defense used by the CPV and KPA, and create advantageous conditions for a further offensive towards Osen Mountain.

A day later the enemy carried out a major assault landing exercise along the east coast, in which more than 100 ships participated in the areas of Thon-Chyon and Koza, and simulated a major landing with a goal of training their forces in detecting countermeasures which could be used as obstacles by the Chinese Volunteers and Peoples Army in case of an aggressive landing by the enemy.

The battle north of Kumhwa developed for Hill 597.9 and on the north slopes of Hill 537.7 and took on a terrible nature, lasting for 43 days.[19]

Hill 597.9 and the north slope of Hill 537.7 were defended by the 8^th, 9^th, and 1st companies of the 135^th Infantry Regiment, 45^th CPV Infantry Division, 15^th CPV Corps.

For three days prior to the start of the offensive the enemy had actively used his artillery and aviation on the front of the defenses of the entire 15^th CPV Corps, and then used the main effort against the objects of the proposed attack – Hill 597.9 and the north slope of Hill 537.7.

With a goal of getting the Chinese Peoples Volunteers to draw the wrong conclusions relative to their main direction of the offensive, the enemy spent several days prior to launching their main strike simulating the withdrawal of their infantry and tanks from Kumhwa towards Chorwon, as they wanted to create the appearance that they were preparing an offensive west of the Hantanchyon River towards Shokimak.

At 0430 hours on 14 October, after a 150 minute artillery preparation and air strikes, after which all of the surface level engineer works (trenches, communications pathways) on Hill 597.9 and the north slope of Hill 537.7 were destroyed, the enemy launched his offensive with seven battalions from the 7^th US and 2^nd ROK Infantry Divisions with the support of 27 tanks and 300 artillery pieces.

The Chinese Volunteers, having skillfully used their engineer works and skillfully launching counterattacks, inflicted heavy losses on the enemy.

But at the same time, by sending in more and more new forces, by 20 October the enemy had taken all of the engineer works on Hill 597.9 and the north slope of Hill 537.7 and forced the Chinese Volunteers to withdraw to their galleries. The continuing battle for the galleries lasted until 29 October.

The enemy, making use of explosive charges, flamethrowers, as well as chemical weapons in some situations, attempted to clear the opposing defenders from the galleries and destroy them. With this goal in mind they destroyed the exits from the galleries, closing the chambers with rocks, sandbags, metallic nets and barbed wire, blew up even the thickest walls of the galleries, threw in bottles of flammable liquids, chemical and incendiary projectiles, and used flamethrowers. But at the same time all of these attempts were futile. The Chinese Volunteers, using the galleries as starting positions, counterattacked the enemy and inflicted heavy losses upon him.

On 30 October the Chinese Volunteers, sending in new forces, launched a powerful counterattack against the enemy on Hill 597.9 and, driving off his subsequent attacks, managed to finally secure it.

Starting on 6 November the primary thrust of the battles changed to the north slope of Hill 537.7. In a series of terrible battles which lasted for 20 days the Chinese Volunteers managed to reestablish their previous positions. By 25 November the battles for Hill 597.9 and the north slope of Hill 537.7 were over.

For that reason, attempts by the enemy to seize Chinese Volunteer positions north of Kumhwa did not meet with success. Taking heavy losses in these battles, he could not achieve his goals.

In the battles for the hills north of Kumhwa significant forces from both sides took part, and combined they number around 100,000 men. In order to seize the hills north of Kumhwa the enemy allocated units of the 7^th and 40^th US Infantry Divisions, the 2^nd and 9^th ROK Infantry Divisions, the 105^th ROK Training Division, and the 2^nd, 3^rd, 5^th, and 8^th ROK Training Center Regiments, 18 battalions of artillery (300 guns), and 120 tanks.[20] Overall the enemy used over 60,000 troops from his side. The offensive was supported by the 5^th Air Force.

On the Chinese side, subunits and units from the 45^th, 29^th, 31^st and 34^th CPV Infantry Divisions took part. These troops were supported by 133 field artillery guns, 292 mortars, and 47 AA guns. The total amount of CPV forces taking part in these battles for the hills was as many as 40,000 men.

All of these forces were committed by first one and then the other side sequentially, based on the situation, but each side had no more than two regiments participating in combat at the same time.

The enemy, as is correct, only advanced in daylight. But at the same time, he continued to move forward in many cases during the hours of darkness.

The offensive by his subunits was normally preceded by artillery and aerial preparatory bombardments, during which the forces in the forward defensive positions were suppressed by the use of regular and incendiary means – napalm. In order to suppress fire support means along the forward edge of the defense tanks were used, engaging them with direct fire.

Enemy attacks were conducted sequentially, on several directions and during the entire daytime period. If his attacks were turned back in one area, he would attack in another. If his attack in the new sector was repulsed, he would turn to attack in the first sector again.

During October and early November, the enemy would begin to move forward with small subunits starting in the morning (before 0800 hours) striving to isolate the Chinese Volunteers and inflict losses upon them. After 0800 hours the enemy would send his first echelon into combat. If they were unsuccessful, he would again launch a 30 or 60 minute artillery bombardment until 1200 hours, when he would send in his second echelon and begin the offensive once more. If he was unsuccessful this time, the enemy would put his forces in order, call up the reserves, and after an indefinite but powerful artillery bombardment would launch all of his forces in an attack before 1500 hours. If the enemy again found no success, he would launch a smokescreen and under cover of that screen, covered by small groups, withdraw to his starting positions. The next day, the enemy would repeat his attacks in this order.

For that reason, the enemy’s operations took on a templated nature, which was successfully exploited by the Chinese Volunteers.

The combat order of enemy units and subunits normally was set up in two echelons with an allocated reserve. Beside that, they created a fire support group, which combined all organic and attached fire support means – machine guns, recoilless rifles antitank rifles ((e.g. bazookas)), and mortars. These fire support means were used to support the infantry attacks. On closing with the enemy, the Americans took up a dispersed order, but in the attack they tightened up their combat order, which as a result caused them to take heavy losses among their troops.

The combat order of the South Korean forces was more dispersed than the Americans, but their attacks were carried out rapidly and resolutely. But not finding success, the South Korean subunits rapidly changed the direction in their attacks and methods of operation, and therefore took fewer losses from Chinese Volunteer fire.

During their attacks, the American forces strove to envelop CPV strong points and attack them from the flanks and rear, but at the same time, frequently finding themselves enveloped, they rapidly pulled back to their starting positions.

With a goal of organizing cooperation with artillery, the enemy occasionally went into the attack with large red flags. Taking a CPV position, they ran up these flags and the artillery would then cease fire. If the attack was turned back, the enemy pulled them down, and the artillery would again begin firing.

After seizing Chinese Volunteer positions, the enemy would immediately proceed to strengthen them. But at the same time, the CPV, rapidly launching a counterattack, frequently did not give the enemy the chance to organize a system of fires and secure the positions taken, and therefore the Americans could not hold them and under strikes from the Chinese Volunteers withdrew to their starting positions.

The Americans had steadfast cooperation among their infantry, artillery and aviation in combat, which as is correct, was not disrupted. Artillery and aviation were always on call to the infantry to provide timely and effective support. Such cooperation among the South Koreans was much poorer, unreliable and therefore frequently broke down.

In the battles north of Kumhwa the enemy, in order to screen his movements and maneuver of his forces, made wide use of smoke, for which he employed artillery and aviation.

Depending upon his established goals, the enemy set up smokescreens within the depth of his dispositions, inside the depths of the CPV defensive positions, and immediately upon the battlefield. The duration of the smokescreens depended upon the actual complexity of the situation and varied from several minutes to 8-10 hours.

With the goal of creating advantageous conditions for night operations by their forces, the enemy used illumination means in the battles north of Kumhwa – searchlights, installed on the hills in the depths of their dispositions, illumination shells and illumination bombs. When they captured CPV positions, the enemy began to illuminate the terrain intensively, often for the entire night.

CPV forces operations in the battles north of Kumhwa were skillful and aggressive. During artillery and aviation preparatory bombardments by the enemy, personnel took cover in the galleries. Only observers were left in the positions (most of those were platoon observers) and radio operations which, carefully observing the enemy, maintained communications with the galleries and the artillery. As soon as the enemy shifted his artillery fires into the depths of the defense, on signal from the observers the subunits would quickly leave the galleries and take up their combat positions to repulse the attack.

Not all of the subunits would leave the galleries, but only that part of them considered necessary to turn back the enemy attack. The rest remained in reserve, ready to support those subunits which were fighting.

Fire on the attacking enemy commenced, as is correct, suddenly and at close range. When repulsing enemy attacks the Chinese Volunteers made wide use of hand grenades and explosive charges. After repulsing an attack they, in order to avoid taking casualties from enemy artillery fire, would rapidly return to their galleries.

In the battles north of Kumhwa the Chinese Volunteers were highly aggressive in counterattacking the advancing enemy. Counterattacks were carried out, as is correct, with surprise and mainly at night, and against the enemy where he had not succeeded in strengthening the defenses and put himself in order.

When the enemy seized their ground-level positions, the Chinese Volunteers would withdraw to their galleries, from which they would launch counterattacks against isolated enemy subunits in order to not give them the opportunity to change positions, and by inflicting losses on him create advantageous conditions to launch counterattacks from the depths of the defense. Their operations took on an impudent but skillful nature. For operating on the surface, they used small groups of 5-10 men, armed with automatic weapons and explosive charges. Under cover of darkness these groups would sneak out of their galleries and suddenly inflict a strike against those blockading the galleries, inflicting losses on the enemy. Operating from the galleries, the forces harassed the enemy to put stress on him, confusing him and preventing him from having the ability to destroy the galleries. The struggle to hold the galleries and destroy the enemy on the surface was carried out in cooperation with units defending outside the galleries.

Special attention was paid to the defense of the entrances to the galleries. The entrances were defended by specially allocated groups for this purpose. All attempts by the enemy to blockade them, and then destroy the galleries used by the Chinese Volunteers were given the highest priority to disrupt. Joint operations by forces defending the galleries and forces located outside them meant that the enemy forces who seized the surface positions would be destroyed or driven back to their staring positions.

For that reason, the battles north of Kumhwa showed that consideration of the galleries as part of the system of trenches and communications pathways provided for increased steadfastness and survivability of the defenses. Powerful artillery bombardments and air strikes were not able to destroy the galleries and wipe out their defenders. The defense by the Chinese Volunteer forces became invincible.

After the battles north of Kumhwa combat operations by the sides were limited to artillery registration fires, the conduct of reconnaissance, and battles for individual hills. In the conduct of the battles between the sides, both sides made use of small subunits from platoon to battalion level, and on rare occasions, two or three battalions or a regiment. In their organization and conduct these battles were fought by the Unified Command of the CPV and KPA with the primary goals of destroying enemy troops and teaching their forces combat experience.

Combat operations by CPV and KPA aviation during 1952 was primarily limited to the main function of protecting important objects located in the northern regions of the DPRK and northeast China, and occasionally covering their forces.

Combat operations by American aviation, in spite of the limited scale of operations on the ground front, were reasonably active. On average the UN forces launched up to 800 combat sorties per day.

In 1952, together with the significant increase in opposition by CPV and KPA fighter aviation, and due to this increase a rise in the threat to UN air superiority, the American command was forced to increase its fighter aviation. Beside that, heavy losses taken by tactical bomber aviation units (equipped with B-26 bombers) in daylight, forced the American command to switch over to making exclusive use of these bombers at night.

During the course of combat operations in 1952, it was shown that in spite of the significant activity by their aviation, the enemy was not able to achieve the desired results and as a whole could not support the corresponding concepts of the American command.

The KPA Navy defended the western and eastern coasts, as well as carried out mining operations in coastal waters.

The UN naval forces, which at the end of 1952 had more than 180 warships and 120 auxiliaries and landing vessels, correspondingly continued to blockade the coasts of the DPRK. In this the primary grouping of vessels was active off the east coast.

The Unified Command, considering that in the spring of 1953 the enemy could go over to the offensive and land major naval landings, carried out additional measures between January and the first half of March to reinforce the defenses, especially along the east and west coasts.

With this goal in mind, the 1^st, 16^th and 54^th CPV Corps were transferred from China to Korea along with reinforcing units and an operational regrouping of forces took place, with the result that the 15^th, 38^th and 40^th CPV Corps, having acquired a great deal of combat experience, were withdrawn from the front and moved as follows:

The 38^th and 40^th CPV Corps were used to reinforce the defense on the west coast, and the 15^th CPV Corps was sent to reinforce the defense on the east coast. They were replaced on the front lines by sending in the 23^rd, 24^th and 45^th CPV Corps. Simultaneously measures were taken for further engineer work on the defenses. Beside that, in order to contain the enemy and inflict losses upon him, in May 1953 plans were made and offensive operations conducted along the entire front, with the result that around 7,000 enemy soldiers and officers were wiped out.

Combat operations by American aviation during this period were reasonably active. On average they flew 700 to 1,000 sorties per day, striking the combat order of the forces, rear area objectives and lines of communication of the CPV and KPA, as well as continue massive bombing of the chain of hydroelectric plants on the Changchin River (15-45 kilometers northwest of Hamhung), the Hotchen River (125 kilometers northeast of Hamhung), and the Supung hydroelectric plant on the Yalu River. Beside that, the enemy carried out raids on the cities of the DPRK.

During the course of combat operations, the methods used by enemy aviation underwent some changes. If in 1952 their aircraft operated in small groups of 8-24 aircraft, then in 1953 the Americans began to use groups of 70-200 aircraft. In order to support operations by their bombers, they formed immediate cover groups and screens consisting of 60-100 jet fighters patrolling in front of the area of operations by the bombers or on the most probable axes of attack by CPV or KPA fighter aviation.

The UN naval forces took an active part in combat operations. At any one time the enemy allocated 30-40 warships, 20-25 special purpose vessels, and up to 350 aircraft based both on land and on carriers to blockade the coasts. The naval warships and aircraft, operating in Korean waters, conducted mine sweeping, systematic bombardment of the Korean ports from the sea as well as other objects along the coastline, and provided fire support to troops along the (eastern) coastal sector of the front, as well as bombardment and bombing strikes against the forces and settlements both along the coast as well as in internal regions. The most frequent victims of these bombardments were coastal cities.

In early 1953 the governments of the Peoples Republic of China and the Democratic Peoples Republic of Korea again took the initiative to focus on the achievement of an agreement for a ceasefire and an end to the war in Korea . On 30-31 March 1953 the PRC and DPRK governments published a declaration in which they stressed the necessity for an immediate start to negotiations on the exchange of sick and wounded prisoners of war, as well as moving towards firm proposals on the regulation of the question of prisoners of war as a whole and the achievement of an agreement to end the war in Korea.

Under pressure from world societal opinion the USA was forced to make a decision. On 11 April they signed an agreement on repatriation of sick and wounded prisoners of war and on 8 July – an agreement on the question of repatriation of all military prisoners of war. On 16 July the demarcation line was amended and agreed upon. All points brought up at the conference were agreed upon.

But at the same time, with the renewal of the negotiations on a ceasefire the South Korean government began a broad campaign focused on breaking them off, threatening to “independently” carry on with combat operations. In conjunction with this, in July 1953 the command of the Chinese Volunteers made the decision to use the forces of the 20^th CPV Army to carry out an offensive operation between 13-18 July with the goal of destroying units of the Capital, 6^th, 8^th and 3^rd ROK Infantry Divisions and taking an area south and southeast of Kimsong.

It was decided that the main strike would be made by the 68^th CPV Corps from the line Yul’don – Kimsong (a front of 8 kilometers) in the general direction of Wol’poni – Tuyul’ton with the mission of crushing units of the Capital and 6^th ROK Infantry Divisions, and the 67^th CPV Corps would advance from the line Huchong – Sam’yendong (a front of 8 kilometers) in the direction of the Kaemsan Mountains – Sizunni with the task of crushing units of the 6^th and 8^th ROK Infantry Divisions.

An additional strike would be launched by the 60^th CPV Corps from the line Chasudong – Hill 994 (a front of 8 kilometers) with the mission of advancing in a southwesterly direction and crushing units of the 8^th and 3^rd ROK Infantry Divisions. As opposed to the formations of the other corps, this corps was operating in two echelons.

With the goal of reliably supporting the right flank of the 68^th CPV Corps, formations of the 24^th CPV Corps were given the mission to advance in the general direction of Hasori – Sondong and not permit counterattacks by units of the 9^th ROK Infantry Division nor the left flank units of the Capital Infantry Division against the flanks of the 68^th CPV Corps.

To support the left flank of the 60^th CPV Corps the formations of the 21^st CPV Corps were given the mission to aggressively operate to cut off units of the 7^th and 20^th ROK Infantry Divisions.

In order to develop the success of the 67^th and 68^th CPV Corps in the general direction of Hwachen, the 20^th CPV Army allocated the 134^th and 135^th CPV Infantry Divisions of the 54^th CPV Corps, the 202^nd CPV Infantry Division of the 68^th CPV Corps, and the 201^st CPV Infantry Division of the 67^th CPV Corps, which were deployed in the areas of Saepori, Sanbau, Tunamni and east of Chyangori. In all 16 infantry divisions were allocated to conduct the operation.

The 20^th CPV Army was to advance along a front of 32 kilometers (from Chuchaton to Hill 994) with 7 infantry divisions in the first echelon, one division in the second echelon of the 60^th CPV Corps, and four infantry divisions in reserve. The average operational density was 2.7 kilometers per division.

On this direction the enemy had four divisions in his first echelon (the Capital, 6^th, 8^th and 3^rd ROK Infantry Divisions) and two divisions in reserve (the 5^th and 11^th ROK Infantry Divisions.) Beside that, the 2^nd US Infantry Division was in the vicinity of Sinypni and the 40^th US Infantry Division was in the vicinity of Indae.

The overall correlation of forces (less the 2^nd and 40^th US Infantry Divisions) in the zone of the offensive was 2:1 in favor of the Chinese Volunteers. The enemy had an absolute superiority in aircraft and tanks.

At 2100 hours on 13 July the forces of the 20^th CPV Army went over to the offensive. Overcoming stiff enemy opposition, by 1100 hours on 14 July 1953 they had moved 3-6 kilometers into the depths of the enemy’s defense and were fighting along the lines: 68^th CPV Corps – Turye, Kampunton, Songdi; 67^th CPV Corps – Songdi, Kamokol’, Keamsan Mountain; 60^th CPV Corps – Chibsili, Kwanteton, Yandi.

With the goal of saving his troops and military technology, the enemy was forced to hastily pull back the units of the Capital, 6^th and 8^th ROK Infantry Divisions to the south. Simultaneously, with the goal of halting the advance of the Chinese Volunteers, he began to bring up his reserves in the form of the units of the 5^th and 11^th ROK Infantry Divisions into the area of combat operations.

Pursuing the withdrawing enemy and using weather conditions (rain) in their favor, which prevented the enemy from using his aviation, the forces of the 20^th CPV Army had moved 3-8 kilometers by the end of the day on 14 July 1953 and were along these lines: 68^th CPV Corps – Bandon, Kandihen, Tuyul’ton; 67^th CPV Corps – Tuyul’ton, Sinzunni; 60^th CPV Corps – north bank of the Kimsong River. The corps received the mission to fortify the line they had achieved, resupply with ammunition and provisions, evacuated captured enemy technology, and use forward detachments to pursue the retreating enemy in a southerly direction.

The 72^nd and 74^th CPV Infantry Divisions of the 24^th CPV Corps, having carried out their mission to support the right flank of the forces of the 68^th CPV Corps, moved into the depths of the enemy’s defenses a distance of 1-3 kilometers and by the end of the day on 14 July had their main body occupying the line Galgol – Hill 432. The divisions received a mission to dig in along this line, paying special attention to the Kumhwa – Kimsong highway, and use forward detachments to continue the pursuit of the retreating enemy in the direction of Kompoonri – Ankol’.

The forward detachments, having carried out their assigned missions, had reached the line Bonmi – Synam-Kogae Pass – Chupari – Hinbau Mountain – Hill 818 by 1700 hours on 16 July, where they ran into resistance and counterattacks by leading units of the 3^rd US Infantry Division and the 5^th and 1^st ROK Infantry Divisions.

During the 17^th and first half of 18 July the formations of the 24^th CPV Corps of the 9^th CPV Army and the 68^th, 67^th, 60^th and 54^th CPV Corps of the 20^th CPV Army fought a stiff battle along the line they had achieved. Further movement forward had been halted by strong counterattacks by the units of the Capital, 6^th, 11^th, 5^th, 8^th and 3^rd ROK Infantry Divisions and the 3^rd US Infantry Division, supported by massive air strikes. Under a difficult situation the command of the CPV forces decided, using rear guards to hold off counterattacking enemy units, to pull back the forces of the 67^th and 60^th CPV Corps to the north bank of the Kimsong River and have them dig in there. During the first half of the 18^th the main bodies of the 67^th and 60^th CPV Corps began to retreat, but by the end of the day the formations had occupied the defensive line Hill 432 – Isilgol – Tuyul’ton – Sizunni – north bank of the Kimsong River . All attempts by the enemy to break through in a northerly direction were repulsed by the forces of the 20^th CPV Army.

During the course of the operation the 20^th CPV Army took 3,190 enemy soldiers and officers prisoner, captured 153 weapons, 50 tanks, 29 mortars, 187 trucks, 110 machine guns, shot down 10 and damaged 20 enemy aircraft.

The offensive by the CPV forces in July 1953 was one of the largest operations carried out by them during the fourth phase of the war in Korea . They deployed along a 45 kilometer front and continued to move forward for three full days.[21] They reached a depth of penetration of 15 kilometers with an average speed of advance of 5 kilometers per day. As a result of this offensive the enemy suffered new losses. Penetrations into the depths of the Chinese defenses were liquidated and the front line was evened up south of the Kimsong River .

This offensive demonstrated the growing mastery and skill of the CPV Command in organizing and conducting an offensive with a breakthrough of a prepared enemy defense. The CPV forces during this offensive operated skillfully and brazenly. Operating mainly at night, they skillfully reached the enemy strong points, got between them and struck from the flanks and rear in order to destroy the defending enemy. Their use of night operations limited the enemy in his ability to take full measure in use of his aviation forces and reduced the losses among the advancing troops.

At 1000 hours Korean Time on 27 July the warring sides signed the agreement for a ceasefire at Panmunjong. In accordance with this agreement, at 2200 hours combat operations along the entire front would cease. The war in Korea was over.

The line of contact of the forces of the sides at this time ran from: the delta of the Imjin River – Orichon – Sizunni – Chungsimpo – Changson – Phoyedin. Along this line is where the demarcation line ran. Under conditions of the agreement both sides had to destroy and abandon their defensive works to a depth of two kilometers back from this line by 31 July, creating a demilitarized zone.

The force grouping of troops of the sides at the moment of the signing of the agreement was as follows.

The CPV forces occupied a line from the delta of the Yesong River to Chungsimpo covering 170 kilometers, and had nine corps of the 19^th, 9^th and 20^th CPV Armies on that line. The 19^th CPV Army defended 80 kilometers of the line from the delta of the Yesong River to Syiyan with three corps (the 65^th, 46^th, and 1^st CPV Corps). The 63^rd CPV Corps defended the coast from Haeju to the delta of the Yesong River . The 64^th CPV Corps was concentrated in the vicinity of Sariwon, Techunni, and Chunfa. The 9^th CPV Army, consisting of three corps, had its operational formation in one echelon, defended the line from Syiyan – Hasori over 45 kilometers. The 30 kilometers of the line from Hasori – Ongol’ was defended by three corps of the 20^th CPV Army. The second echelon of the army, the 54^th CPV Corps, was concentrated in the area northeast of Sapori. The zone from Ongol’-Chungsimpo of 15 kilometers was defended by the 21^st Independent CPV Corps.

From Chungsimpo to the east coast the line stretched 55 kilometers and was covered by the forces of the 3^rd and 7^th KPA Armies, who had five divisions in this sector.

Overall the 225 kilometer front was defended by 38 divisions, of which 32 were Chinese and 6 were Korean. The average operational density was 6 kilometers per division.[22]

The west coast from Dogushan to the delta of the Yesong River was defended by the forces of the 39^th, 50^th, 40^th and 47^th Independent CPV Corps, the 64^th and 63^rd CPV Corps of the 19^th CPV Army, and two regiments from the 114^th CPV Infantry Division of the 38^th CPV Corps, and forces of the 4^th KPA Army with a total of 23 infantry divisions, three machine gun-artillery brigades, and two infantry regiments. The main body (15 divisions, one machine gun-artillery brigade, and two infantry regiments) were deployed along the Sonchen-Nampo front.

The east coast from Unamni to Uki (80 kilometers north of Chengdin) were defended by the forces of the 1^st, 2^nd and 5^th KPA Armies and the 3^rd CPV Army with a total of 15 divisions and 4 machine gun-artillery brigades. All of these forces (other than two machine gun-artillery brigades) were deployed along the Unamni – Hamhung front.

Overall there were 76 divisions and 7 machine gun-artillery brigades (58 Chinese divisions and 18 KPA divisions and 7 KPA machine gun-artillery brigades) deployed in the DPRK as of 27 July 1953.

The number of personnel and armaments in the ground forces of the CPV and KPA as of 27 July 1953 is shown in Table 18.

Opposing the CPV and KPA forces on 27 July 1953 were the forces of the I, IX and X US Corps and the I, II and III ROK Corps, consisting of 24 divisions (7 were American, 1 British and 16 South Korean) and one brigade[23] Beside that, the Americans and South Koreans had a large number of independent regiments, battalions and special units and subunits in their dispositions. All of these forces were as before located immediately at the front.

The numbers of troops and combat technology with the American and South Korean forces can be seen in Table 19.

The number of ground forces personnel and combat technology at the end of the war, and in spite of the positional nature of the fourth phase, increased, as can be seen in Table 20.

The overall correlation of forces at the end of the war is presented in Table 21.

For that reason, the superiority in numbers of personnel, artillery and mortars at the end of the war remained on the side of the CPV and KPA, but at the same time the UN and South Korean side retained their superiority in tanks and aircraft.

Overall results. The commencement of negotiations over the ceasefire and the conversion of the American forces to positional warfare showed a complete shattering of their plans to seize all of

Korea

. The politics of “a position of strength” which had been the overarching external policy of the USA was bankrupt. All of the subterfuge of the diplomatic and even military order tried during the course of the negotiation did not yield the desired results for the Americans. The ceasefire was concluded.

Characteristic picture of operations by the Chinese Volunteers and the Korean Peoples Army. The defense by the forces of the CPV and KPA during the fourth stage of the war in Korea was created in consideration of the steadfast holding of their positions immediately along the front and the repulsing of possible enemy landings along their coastlines. It took all of the efforts of the troops to carry out this mission.

The defense was structured to a depth of 30-50 kilometers and consisted of three belts and individual fortified areas and nodes. Along the coastlines and in areas where enemy landings were most probable the defense was structured to a depth of 20-50 kilometers. Along these defensive belts fortifications did not form an amalgamated front, but only along the important directions where engineer works could best be developed.

The strength of the mountainous nature of the terrain was used in the engineer defensive belts both at the front and along the coasts, and took on a centric nature. The defensive belts were equipped with a system of covered firing points, trenches and galleries, deployed in layers and connected to each other by communications pathways within the limits of the strong point or defensive node. The most complete engineer works using terrain were on the forward edge of the defense and to a lesser degree in the depths of the defense.

The layered disposition of firing works and the presence of trenches with a large number of galleries was one of the characteristics and promising pictures of engineer works using terrain. The layer disposition of firing works provided for a multilayer system of fires, fire support from the lower levels of the works, and increased density of infantry fires in front of the forward edge of the defense.

The presence of galleries in the defenses of the CPV and KPA forces provided for saving the troops and combat technology during the artillery and aviation bombardments and rapidly opening fire on the enemy as they went over to the attack. Beside that, the galleries permitted the rapid, secure and safe introduction of troops to the deployment lines for counterattacks and that in and of itself sharply reduced the expenditure of time and resources to move to these lines. Along with that the galleries provided surprise in launching counterattacks. They were equipped with consideration that they would permit the effective use of fire support assets, could rapidly be occupied by troops from their surface positions, permitted maneuver of troops within the limits of their strong points or defensive nodes, and permitted the secret accumulation of forces and surprise launching of counterattacks. With all of these promising qualities the galleries and other underground works still did not reduce the role and significance of trenches and communications pathways in the defense.

To steadfastly hold terrain subunits, units and formations, based on the nature of the terrain and the importance of the direction immediately to their front, were allocated regions, sectors and belts of the following widths: company – 700-2700 meters; battalion – 500-7000 meters; regiment – 2-10 kilometers; division – 9-16 kilometers, corps (CPV) or army (KPA) – 15-30 kilometers, and on occasion more. Along the coast the width of the regions, sectors and defensive belts was larger and constituted: company – 2.5-3.5 kilometers; battalion – 5-7 kilometers; regiment – 9-15 kilometers; division – 20-36 kilometers; and corps (Korean army) – up to 80 kilometers or more. The basis for mountainous defense both at the front as well as along the coast was the company strong point, equipped with galleries and connected with a system of trenches and communications pathways. In broad valleys and on open terrain, the basis for the defense was the battalion defensive area.

Operations by CPV and KPA forces in the defense were solid, skillful and aggressive, which constituted one of the characteristic and normal methods by which they conducted combat. Allocated a well-developed system of engineer works fitted to the terrain for their operations, they would turn back attacks by a numerically superior enemy and inflict heavy losses upon him. Fires against the attacking enemy that were intended to inflict heavy losses upon him by the CPV and KPA forces were, as is correct, opened with surprise and at close range. In this wide use was made of hand grenades. Such fires shattered the enemy and were very effective.

Counterattacks against a pinned-down enemy were launched with surprise and speed. This compromised one of the most important characteristics and promising pictures of operations by the CPV and KPA forces in the defense. Continuous and skillful operations by the forces confused the enemy and did not permit him to organize a defense of positions he had taken. Beside that, counterattacks developed an offensive spirit in the forces, which carried over to the conduct of offensive operations and aggressiveness.

With a goal of reducing the effectiveness of enemy fire and air strikes the CPV and KPA forces launched their counterattacks mainly at night, using the lack of training by UN forces to operate under these conditions. By studying the strengths and weaknesses of the enemy side, the CPV and KPA forces, by operating skillfully and decisively, destroyed pinned-down enemy forces or forced him to retreat to his starting positions.

Finding themselves in the defense, the CPV and KPA forces made wide use of offensive combats with company- or battalion-sized units against their opposing enemy strong points. The choice of the place and time of launching a strike, allocation of forces and means, and organization for cooperation were determined by corps commanders. The operations plan was validated by higher commanders.

To support the attack of the company, normally no more than one howitzer or mortar battery was allocated for fire support, and for a battalion 2-3 battalions of howitzer artillery, but the CPV would use one battalion of sixteen mortars and on occasion 3-4 heavy tanks.

The timing of the attack was normally chosen with consideration of suppressing the enemy and destroying his works immediately prior to the advance under darkness. The attack itself was carried out at night.

During the battle for the strong point, and in order to not give the enemy the possibility of retreating into the depths of his defense, artillery fire was placed on the flanks and rear of the strong point.

Holding captured strong points was a mission not given to the offensive subunits, but rather their goal was to wipe enemy troops and combat technology. Therefore when the enemy went over to the counterattack, as is correct, they would abandon these strong points to him.

The characteristic picture of operations by CPV and KPA troops in the defense saw the wide use of ambushes with a goal of wiping out enemy troops and combat technology, terminating enemy reconnaissance, not permitting entrance and capture of strong points by the enemy, and finally, taking prisoners.

Based on its mission, ambushes were set up in front of the forward edge of the defense, in the intervals between strong points, and on occasion in the depths of the enemy’s defense. An ambush normally consisted of a squad or platoon, and on occasion a company. Surprise operations from ambush confused the enemy and created advantageous conditions for rapidly crushing him.

In the defense a major role was played by tanks and self-propelled guns. They were used both immediately on the forward edge of the defense as well as along the coastal defenses. Only the Chinese Volunteers used tanks and self-propelled guns along the forward edge of the defense, and the Peoples Army used theirs along the coastline.

Tanks provided immediate fire support to the infantry during the course of offensive combat with limited missions, operating in small groups (3-4 tanks) and, as is correct, at night or under conditions of limited visibility in daytime. In defensive battles tanks were widely used from ambush. In this the bulk of the tanks were placed in reserve on tank accessible terrain and designated to conduct the counterattack. Tanks in the defense during this phase of the war were widely used in firing from concealed positions. In some cases tanks were used in direct fire mode. But at the same time, this method of operations did not see wide use.

In seacoast defense tanks were mainly used as part of combined arms units and on the directions where enemy landings were most probable. Normally one-third of the tanks and self-propelled guns were allocated directly for beach defense, and the remainder were used as a tank reserve and deployed in the depths of the defense. Tanks were effectively used in combating enemy warships.

The characteristic picture of the use of artillery was such that it operated mainly from concealed positions, generally of the covered tunnel-type fortifications. In isolated cases individual weapons were used for direct fire.

Firing positions for the artillery were located on the slopes of hills, 4-8 kilometers from the forward edge of the defense, and with consideration that the majority of the weapons were able to concentrate their fires on the direction from which the enemy was most likely to launch his main strike. Tunnels reliably protected the guns from enemy artillery fire and air strikes, thus increasing their survivability. But at the same time it limited the ability of the artillery to use maneuver by fire.

In seacoast defense the majority of the artillery was concentrated in those places where the enemy was most likely to make a landing. In this the main effort of the artillery would be focused on destroying the landing during their approach to the beach and once upon the beach. Their firing positions were again the covered tunnel type, which reliably protected the guns from enemy naval gunfire and air strikes. Combating warships conducting coastal reconnaissance was provided by guns specially allocated for this mission, which would fire at them from temporary firing positions.

During the course of the fourth phase of the war CPV and KPA forces conducted offensives. In this they would advance mainly at night or under conditions of limited visibility (rain, fog) during the day. This obviated enemy air superiority and limited the use of the large number of fire support means in his defenses.

Night simplified concealing the concentration of troops, secrecy and surprise of their operations, and most importantly, it ensured that fires from the enemy defenders and use of his aviation would only be minimally effective.

By using this supremacy, the CPV and KPA forces, as is correct, achieved victory. To a significant measure this was aided by the unpreparedness of the enemy in conducting combat under nighttime conditions.

In order to limit the ability of the enemy to organize a withdrawal and occupy new defensive positions, the CPV and KPA forces, going over to the offensive, operated with speed and skill. Such operations by CPV and KPA forces permitted them to reliably hold territory, which then ensure they could reliably turn back counterattacks.

To hold terrain they created engineer works as well as used similar works built by the enemy, whose forces had rapidly gone over to the defense.

During the course of the offensive the CPV and KPA forces made wide use of maneuver with the goal of reaching and taking enemy strong points, skillfully pinning down his defenders and wiping them out by striking them from the flanks and rear.

Characteristic picture of the operations of the American and South Korean forces. The defenses of UN forces and the South Korean army differed from the defenses of the CPV and KPA forces as they were only structured to hold terrain at the front. The defense of the coasts was left to the supremacy of their naval forces and thus did not need to be created.

The defense was structured to a depth of 15-45 kilometers and consisted of two belts, with intermediary positions between them. The basis of the defense consisted of battalion nodes of resistance, provided with a system of covered firing positions, trenches and communications pathways.

The nodes of resistance were located in the most tactically important sectors of terrain and prepared for all around defense. The intermediary points between the nodes of resistance were covered by artillery fires and engineer obstacles. With a significant number of intermediary positions between the nodes of resistance a reasonably large group of infantry were assigned to cover them, which they did and also set up strong points.

To hold terrain the forces received areas, sectors and belts based on the importance of the direction: battalions – 2-3 kilometers; regiments – 5 kilometers; divisions – 10-18 kilometers; and corps – 30-70 kilometers. Such broad regions, sectors and defensive belts, in spite of the mountainous terrain in the area of combat operations, approached the norms for defense on average broken terrain.

The high level of activity by CPV and KPA forces, especially at night, forced the UN forces to make wide use of antipersonnel obstacles. In this the greatest density of antipersonnel barriers were created in front of the forward edge of the defense, as well as along mountain passageways, roads and paths which crossed the defensive positions.

Active nighttime defense by the CPV and KPA forces saw wide use by South Korean forces of signal-illumination means (rockets, mines, explosives) which were set up on the approaches to minefields and wire obstacles or immediately within these means, which signaled them of the approach of the enemy to these obstacles as well as illuminate the terrain during nighttime. The Americans used a new method of obstacles at night – napalm mines and fugasse, which were simultaneously used to illuminate the terrain. Beside that, with a goal of creating advantageous conditions for operations by their forces at night, the Americans made wide use of searchlights installed on the hills in the depths of their defense, as well as illumination shells and bombs.

When they pinned down CPV and KPA forces in the defense, UN forces would go over to the counterattack, which took place only in daylight and, as is correct, after artillery and aviation preparatory bombardment. This permitted the CPV and KPA forces to use the hours of darkness to strengthen their captured positions and in most case succeed in driving off these counterattacks. With a goal of achieving surprise the Americans on occasion would launch their counterattacks without artillery or air strikes.

On tank accessible terrain the infantry would launch its counterattacks with tanks and self-propelled antiaircraft guns. If the terrain did not favor the use of tanks in the combat order of the infantry, the tanks would provide them with fire support from the halt.

Counterattacks were repeated when the outcome of the battle was unsuccessful. In this, if they could not retake the positions that had been taken by the CPV and KPA forces, they would conduct a long artillery and aviation bombardment of the positions with the goal of eliminating the forces located there.

During the course of conducting defensive battles the American forces showed that they were unprepared to conduct combat operations at night, and were very vulnerable to being approached and having their positions taken from the flanks. Their forces, as is correct, did not fight at night and remained in their positions.

The South Korean army, in spite of their much lower level of technology, were active and steadfast in the defense, and did not wait on American forces. They were able to make skillful use of the terrain, were less vulnerable to approaches and having their positions taken from the flanks, and reasonably skillful at night operations.

The UN forces in the defense made wide use of ambushes with the goal of terminating enemy reconnaissance and seizing prisoners. The ambushes were mostly set up in front of the forward edge of the defense, in places where it was most likely to take individual CPV and KPA soldiers, and primarily at night.

To set up an ambush the American forces created special groups, whose makeup depended upon their assigned mission and how far the ambush was to be established from their positions. The groups normally included a squad to a platoon of infantry, reinforced by light machine guns.

The Americans made wide use of operations by reinforced infantry in the defense, and on occasion tank subunits (platoon to company size) with the goal of conducting reconnaissance, diversionary operations (the main reason being to destroy defensive works along the forward edge of the defense) and raids. The depth of operations of these subunits was primarily limited to the basic area of battalion defense against first echelon CPV and KPA units. Infantry subunits during the execution of these missions normally were supported by artillery fire and tanks, which destroyed the firing points, cut off enemy movement, and destroyed earth-and-wood engineer works.

These subunits operated both at night and in daylight, but their greatest use was at night. When operating at night to carry out their missions they mostly consisted of infantry. Artillery, mortars, and tanks provided support to their operations using preplanned fires, which for the most part were used to isolate the objective of their attack.

Missions allocated for daylight hours were mostly those carried out to conduct reconnaissance and observation of the battlefield. When carrying out these observation missions no more than one infantry squad was allocated, but carrying out combat missions called for allocations of subunits of up to a reinforced company in strength. Combat missions were carried out the same as a normal offensive operation.

The Americans used tanks in the defense in small subunits, which were given the following missions: reinforce the antitank defense of infantry subunits, support for infantry subunit counterattacks, destroy earth-and-wood engineer works by direct fire, and operate as part of a patrol.

Tanks were widely used in firing from concealed positions, where their fires were corrected by forward observers.

Artillery during this phase of the war was used in a much more massive nature. As is correct, one to three battalions were used simultaneously to suppress or destroy a single object (target). During daylight hours artillery fire was conducted against targets located in the depths of the Chinese Volunteers and Peoples Army defenses, and in the evening and at night – for the most part against the forward edge of the defense. The expenditure of ammunition, in spite of the positional nature of the war, increased. Enemy artillery expended from 15,000-40,000 rounds per day.

UN and South Korean offensive operations during the fourth phase of the war were planned with only limited goals in mind, which to a great extent determined the nature of their conduct.

During the course of the offensive CPV and KPA strong points and defensive nodes were sequentially engaged by artillery and air strikes, after which the infantry subunits went in. The offensive developed slowly, took on an indecisive nature, and for the most part saw straight-line movement of forces.

Massing of forces and means on any one direction was not carried out. The offensive was conducted by independent reinforced regiments and battalions along selected directions. Divisions, advancing with individual regiments and battalions, operated in belts 8-10 kilometers wide.

The offensive, as is correct, was preceded by a powerful artillery and air preparatory bombardment, which on occasion lasted up to three days. With the shift in fires to the depths of the defense by artillery and mortars, infantry subunits, and on tank accessible approaches, infantry and tanks went over to the offensive. In those cases where the offensive took place on terrain not amenable to tanks, they provided fire support to the infantry from the halt.

The attack was carried out, as is correct, in a compact combat order, so that it suffered heavy combat losses in personnel and technology, and became one of the limiting factors of American forces in the offense. If the subunits moving forward were stopped by fire from the defenders, then the artillery and aviation bombardment was repeated. If after this the offensive was stopped, then the missions to be executed were changed or a long artillery preparation of the defense took place until the positions had been completely suppressed by artillery and aviation.

When strong points were seized, the Americans rapidly turned these positions to use as a defense, making wide use of all available engineer obstacles. The rapid strengthening of captured objectives and the wide use of these engineer obstacles were one of the strongest factors of operations by the Americans in the offensive.

But the weakest factor of the operations by American forces in the offensive came from the fact that their infantry, just as in the defense, was not able to independently conduct combat using all of their firepower. With limited support from artillery, tanks and aviation, they, as is correct, had to withdraw to their starting positions. With the coming of night and under conditions of limited visibility American forces had to break off offensive operations and subunits had to stop on the lines they had achieved or withdraw to more advantageous postions.

[1] Note: This is an updated and edited version of the original 1954 text, and the authors have inserted post-1954 information into the text where it is relative. This expands and modifies many of the original conclusions as well as provides a better view of UN operations generally with the correct units and designations for the opposing side. Translator

[2] The assessment of density does not include four divisions of the 1^st and 3^rd KPA Armies covering the flanks and defending the coastlines.

[3] The 26^th and 23^rd KPA Marine Brigades are counted as one division.

[4] On 31 July 1951 the 63^rd KPA Marine Brigade was redesignated as the 25^th KPA Marine Brigade.

[5] The 24^th and 63^rd KPA Marine Brigades are counted as one division.

[6] Two of these were allocated to the 1^st CPV Tank Division, whose tanks provided immediate fire support to the infantry.

[7] “Crew” varies from aircraft to aircraft, but in this case it means only 60 pilots. Translator

[8] Most of these divisions were up to 15% below strength.

[9] Nine independent battalions or three independent infantry regiments or two infantry brigades were considered as equal to one division.

[10] This is without consideration of the independent regiments and battalions in the reserve of the American and South Korean command.

[11] The 1^st British Division was created on 28 July 1951. It consisted of the 28^thand 29^th British and 25^th Canadian Brigades.

[12] This does not count the 8^th and 47^th KPA Infantry Divisions of the 1^st KPA Army, which were moved to the eastern sector of the front.

[13] This depth does not take into consideration the forces of the 6^th KPA Army, which was defending the coast.

[14] In early October 1951 the KPA marine brigades were reformed as machine gun artillery brigades and resubordinated to the Navy Headquarters.

[15] These included the 8^th and 47^th KPA Infantry Divisions of the 1^st KPA Army.

[16] The 5^th KPA Army, defending on the east coast, was subordinated to the Supreme High Command of the KPA.

[17] The type and nature of these works is described in Chapter 13.

[18] These operations by American forces were referred to in Chinese literature as “the war of asphyxiation.”

[19] In Chinese literature the battles north of Kumhwa were called the “Shangan’lin Operation.”

[20] The 40^th US Infantry Division was transferred to Korea from Japan in January 1952.

[21] The last two days of the operation saw the 20^th CPV Army fighting a defensive battle during the withdrawal to the Kimsong River .

[22] The depth calculation does not take the 7^th KPA Army into account, as it was defending the coast in the Koson and Unamni sectors.

[23] The II and III ROK Corps were newly formed: the first in April 1952 and the second in April 1953.

	CPV Forces	KPA Forces	Total
Personnel	948,299	393,014	1,341,313
Field Artillery Weapons	1,249	731	1,980
Mortars	1,664/73*	1,248	2,912/73
AT Weapons	498	537	1,035
Tanks and SP Guns	118	243	361
Aircraft	452	136	588, of which 318 were fighters

	US Forces	ROK Forces	Others	Total
Personnel	220,000	250,000	35,500	505,000
Field artillery weapons	500	300	80	880
Mortars	400	700	56	1,156
AT Weapons	600	150	48	798
AA Weapons	400	-	-	400
Tanks and SP Guns	700	-	120	820
Aircraft	1,495	-	100	1,595*

	CPV and KPA Forces	UN and ROK Forces	Ratio
Personnel	1,341,313	505,000	2.7:1
Field Artillery weapons	1,980	880	2.2:1
Mortars	2,912	1,156	2.5:1
AT weapons	1,035	798	1.3:1
AA weapons	1,028	400	2.6:1
Tanks and SP Guns	361	820	1:2.2
Aircraft	588	1,595	1:2.7

	CPV and KPA Forces	UN and ROK Forces	Ratio
Personnel	423,416	345,000	1.2:1
Field Artillery weapons	1,219	880	1.4:1
Mortars	1,056/73*	1,156	1:1
AT weapons	539	798	1:1.5
AA weapons	170	352	1:2
Tanks and SP Guns	118	820	1:7
Aircraft	-	1,020	-