Picatinny Arsenal was tasked to create a nuclear capable artillery piece in 1949. Robert Schwartz, the engineer who created the preliminary designs, essentially scaled up the shell (then the maximum in the arsenal) to and used the similarly-sized German K5 railroad gun as a point of departure for the carriage. (The name "Atomic Annie" likely derives from the nickname "Anzio Annie" given to a pair of German K5 guns which were employed against the American landings in Italy.) The design was approved by the Pentagon, largely through the intervention of Samuel Feltman, chief of the ballistics section of the ordnance department's research and development division. A three-year developmental effort followed. The project proceeded quickly enough to produce a demonstration model to participate in Dwight D. Eisenhower's inaugural parade in January 1953. The gun was initially designated T131 and the carriage was T72.