In 1957, the Army decided that in the era of battlefield atomic weapons, tactical infantry regiments were obsolete. To preserve the historic infantry regiments the Army set up the Combat Arms Regimental System (CARS) whereby the line companies of a regiment would form new elements of the regiment. The 12th Infantry was selected as one of the historic regiments to be preserved. On 1 August 1957, Company A was redesignated and activated as Headquarters Company, 1st Battle Group, 12th Infantry (with organic companies of the battle group constituted and activated) and assigned to the 4th Infantry Division. Company B formed the 2nd Battle Group, 12th Infantry assigned in Germany to the 8th Infantry Division until 1959 when it was reassigned to the 1st Infantry Division also in Germany. Company C was allocated to the Army Reserves and formed the 3rd Battle Group, 12th Infantry assigned to the 79th Infantry Division.