The &bThompson &fis a sub-machine gun invented by &eJohn &eT. &eThompson &fin &a1918&f. This weapon was adopted by the U.S. military in &a1938&f, serving during World War II.

There were two variations of the &bThompson &fused during World War II; the &eM1928A1&f, which had provisions for drum and box magazines, and the &eM1 &fand &eM1A1 &fvariants, which had a simplified rear sight and a barrel without cooling fins.