War Machines The U.S. Planned to Use On Japan

More powerful than Germany’s notorious Schwerer Gustav railroad gun, the 40-ton American weapon featured a 22-foot long barrel that could launch a 3,500-lb. (1,600 kg) shell a distance of 6 miles (10 km). But like the T-28 tank, the Little David never fired a single shot in anger; Japan quit before it saw action. A prototype of the massive mortar is on display at the Aberdeen Proving Grounds in Maryland.