 Between 1951 and 1956 the 501st served with the 101st as a Regular Army non-Airborne training unit on two occasions, once at Camp Breckinridge, KY., and once at Fort Jackson, SC.In the spring of 1956, the 501st and the 101st moved (less personnel and equipment) to Fort Campbell, KY, where they were activated as a provisional organization to test the "Pentomic concept.The word pentomic referred to the five battle groups, which were in lieu of regiments and to the division's organic atomic weapon capability.