First US 1st Infantry Regiment Consolidated May-October 1815 with the 5th Infantry (constituted 12 April 1808), the 17th Infantry (constituted 11 January 1812), the 19th Infantry (constituted 26 June 1812), and the 28th Infantry (constituted 29 January 1813) to form the 3d Infantry
Consolidated August-December 1869 with one-half of the US 37th Infantry Regiment (see ANNEX) and consolidated unit designated as the 3d Infantry
(2d and 3d Battalions inactivated 18 November 1921 at Fort Snelling, Minnesota; activated 8 June 1922 at Fort Snelling, Minnesota)
Assigned 24 March 1923 to the 7th Division
Relieved 15 August 1927 from assignment to the 7th Division and assigned to the 6th Division
Relieved 1 October 1933 from assignment to the 6th Division and assigned to the 7th Division
Relieved 16 October 1939 from assignment to the 7th Division and assigned to the 6th Division
Relieved 10 May 1941 from assignment to the 6th Division
(1st Battalion inactivated 1 June 1941 at Fort Leonard Wood, Missouri; activated 14 February 1942 in Newfoundland)
(2d Battalion [less Headquarters and Headquarters Company] inactivated 1 September 1942 at Fort Snelling, Minnesota [Headquarters and Headquarters Company concurrently inactivated in Greenland]; battalion activated 22 October 1943 at Camp Butner, North Carolina)
Inactivated 20 November 1946 in Germany
Regiment (less 2d Battalion) activated 6 April 1948 at Fort Myer, Virginia (2d Battalion concurrently activated at Fort Lesley J. McNair, Washington, D.C.)
Reorganized 1 July 1957 as a parent regiment under the Combat Arms Regimental System
Withdrawn 16 January 1986 from the Combat Arms Regimental System and reorganized under the United States Army Regimental System
