On 15 October 1957, the 40th and 709th Tank Battalions, as well as Troop E, 87th Cavalry Reconnaissance Squadron, were combined to form the 40th Armor under the
Combat Arms Regimental System. Thereafter, elements of the regiment served dispersed among various army commands worldwide. • 1st Medium Tank Battalion, 40th Armor was activated on 15 October 1957 and redesignated Company A, 40th Armor on 16 December of the same year. It was assigned to the
171st Infantry Brigade (
U.S. Army Alaska) on 20 May 1963 and equipped with the
M41 light tank at
Ladd Air Force Base. It was inactivated on 21 September 1969. The battalion was reactivated in 1975 and was subordinated to the
5th Infantry Division,
Fort Polk until it was inactivated in 1987. The battalion was reactivated in January 1996 as an experimental test battalion at
Fort Hunter Liggett, California, then inactivated in September 1997. • 3d Medium Tank Battalion, 40th Armor was activated on 15 October 1957 and subordinated to the
1st Cavalry Division in
Korea. The unit was inactivated on 1 September 1963. • 4th Medium Tank Battalion was formed on 15 October 1957 and redesignated Company D, 40th Armor on 16 December of the same year. The unit was subordinated to the
172nd Infantry Brigade and stationed in Alaska. Later expanded to 4th Battalion, 40th Armor from March 1976 until April 1984, and subordinated to
4th Infantry Division. in West-Berlin. 17 december 1980. • 6th Medium Tank Battalion, 40th Armor was reconstituted on 15 October 1957. The unit was redesignated Company F, 40th Armor on 2 May 1958 and assigned to the U.S. Army's
Berlin Brigade from 1 September 1963 forward. Later it expanded to 6th Battalion, 40th Armor from September 1990 until May 1992. • 7th Medium Tank Battalion, 40th Armor was activated on 1 May 1959. It was redesignated as the 7th Battalion, 40th Armor on 1 April 1963. Subordinated to the 63d Infantry Division and inactivated on 31 December 1965. • 8th Medium Tank Battalion, 40th Armor was formed on 15 October 1957 and assigned on 20 May 1959 to the
96th Infantry Division of the Army Reserve. On 15 February 1963, the unit was redesignated 8th Tank Battalion, 40th Armor, and subordinated to the
191st Infantry Brigade in
Arizona. Final designation was as 8th Battalion, 40th Armor on 12 September 1963. On 12 January 1994, the
Tucson Citizen reported that the unit's function would be transferred to the
Nevada Army National Guard. The unit had been headquartered in at the
Tucson Reserve Center. The 8th Battalion's "mission will be transferred to Nevada. The battalion, with headquarters in Tucson, is slated to be shut down and its mission transferred to Nevada, according to congressional sources.
Congressman Jon Kyl, R-Phoenix, said yesterday that officials associated with the
63d U.S. Army Reserve Command briefed members of the 8/40 over the weekend and, for the first time, informed members of the unit that it will be deactivated. Kyl said mission functions, but not personnel, from the armored unit are set to be transferred to the Nevada National Guard. Kyl said Pentagon officials indicated the deactivation will take effect in 1997. Closure of the 8/40 could result in the loss of 642 Army Reserve positions in Arizona. The unit has companies in Phoenix and
Fort Huachuca that also would be closed under the plan. The unit inactivated in September 1996. ==Twenty-first century==