The Medium Tank M3 was an American tank used during World War II. Design commenced in July 1940, and the first M3s were operational in late 1941. The U.S. Army needed a medium tank armed with a 75 mm gun, and coupled with the United Kingdom's demand for 3,650 medium tanks immediately, the Lee began production by late 1940.
The tank's peculiar design of outfitting the main 75 mm gun in a casemate on the left side of the hull, as well as a fully traversable turret with 37 mm gun, was a compromise meant to produce a tank as soon as possible while the M4 Sherman is still under development.
