FIRST UNITED STATES ARMY CORPS
(I-CORPS)
During the occupation of Japan, I-Corps had its headquarters at Kyoto, Japan, with the 24th and 25th Infantry Divisions, plus supporting units under its command. It was deactivated on 28 March 1950, but with the Korean War, was reactivated at Fort Bragg, NC, on 2 August 1950, with units from the former V-Corps (Fifth Corps) headquarters. I-Corps deployed to Korea on 6 September 1950 and became operational on 13 September 1950 when it assumed command of the 1st Cavalry Division (Dismounted,) the 24th Infantry Division, the 1st Republic of Korea (ROK) Infantry Division, the 27th British Brigade, plus supporting units.
Following the entry of Chinese Communist Forces (CCF) and the retreat of U.N. Forces out of North Korea and back to south of the 38th Parallel, I-Corps was reorganized. In this reorganization I-Corps lost the 1st Calvary Division, 24th Infantry Division and 27th British Brigage, but retained the 1st ROK Infantry Division while assuming command and control for the 3rd Infantry Division the 25th Infantry Division. In April 1951, the 1st ROK Infantry Division was transferred to a newly-formed ROK Army corps and the 1st Calvary Division was reassigned to I-Corps as a replacement for the 1st ROK Division. In December 1951, the 1st Calvary Division was rotated to Japan and replaced at I-Corps by the U.S. 45th Infantry Division (Oklahoma National Guard.) During March 1952, the 25th Infantry Division was transferred from I-Corps command and the 1st Commonwealth Division (British,) the 1st, 8th and 9th ROK Infantry Divisions were added to I-Corps.
A final reorganization took place during January 1953 when I-Corps assumed command of the 2nd, 7th and 25th Army divisions, the 1st U.S. Marine Division and the 1st, 2nd and 15th ROK divisions while losing the 3rd, 24th, 45th U.S. Army divisions, the British Commonwealth Division, plus the 8th & 9th ROK divisions.
Following the ceasefire in 1953, I-Corps remained in Korea until 1971.