The Headquarters and Headquarters Company, 172nd Infantry Brigade, was converted and redesignated the 3rd Platoon, 86th Reconnaissance Troop, and assigned to the 86th Infantry Division on 31 March 1942, while the Headquarters and Headquarters Company, 171st Infantry Brigade, became the remainder of the 86th Reconnaissance Troop. On 15 December 1942 the troop was mobilized and reorganized at Camp Howze, in Gainesville, Texas, as the 86th Cavalry Reconnaissance Troop, only to be reorganized and redesignated again on 5 August 1943 as the "86th Reconnaissance Troop, Mechanized". For the majority of the US involvement in World War II it remained stateside, participating in the Third Army #5 Louisiana Maneuvers in 1943, among other exercises, until finally staging at Camp Myles Standish, at Boston, Massachusetts on 5 February 1945 and shipping out from Boston on 19 February 1945.