1866 - 28 July: Constituted in the Regular Army as the 7th Cavalry Regiment. 1866 - 21 September: Organized at Fort Riley, Kansas, Colonel Andrew J. Smith, commanding. 1833 - Cavalry companies officially designated as Troops. 1917 - December : Assigned to the 15th Cavalry Division. 1918 - 11 May: Relieved from the 15th Cavalry Division. 1921 - 13 September: Assigned to the 1st Cavalry Division. 1943 - 28 February: Dismounted. 1943 - 4 December: Reorganized partly under cavalry and partly under infantry tables of organization and equipment. 1945 - 20 July: Reorganized wholly as infantry, but retained cavalry designations. 1949 - 25 March: Reorganized with troops designated as companies 1957 - 15 October: Relieved from the 1st Cavalry Division 1957 - 01 November: Reorganized as a parent regiment under the Combat Arms Regimental System.