 In order to man the increased number of batteries, the 4.2in mortar batteries in each battle group were removed.The 1961 addition of "Davy Crockett" recoilless spigot guns with atomic warheads supplemented the concept of the atomic age army.Figure 2, "The Pentomic Division", on page 107 of Bacevich's book "The Pentomic Era" shows a graphic from the "Annual Report of the Secretary of Defense for Fiscal Year 1956" depicting the initial ROCID organization.