An American Medium Tank M3, commonly called the "General Lee" (after Robert E. Lee) in Britain, on training exercises at Fort Knox, Kentucky in June, 1942. At the outset of World War II, the M3 was developed as an interim solution to replace the outdated M2, before the M4 Sherman could be mass-produced. A slightly different model was known as the "General Grant" (after Ulysses S. Grant).Photo credit: Alfred T. Palmer, FSA-OWI