By the time the United States Air Force became a standalone service in 1947, the dawning of the jet age was rapidly making our stockpiles of piston-engine aircraft left over from World War II obsolete. Republic Aviation produced over 15,000 P-47s from 1941-1945, and made constant improvements to the aircraft. By the time the United States invaded Normandy, the rugged fighter-bomber could either escort heavy bombers into Europe or devastate Axis ground targets with its eight M2 .50-cal. machineguns and 2,500 pounds of bombs. It was re-designated the F-47 in 1948 and would be retired from active duty Air Force service in 1949.