The term WWII Firearm can be summarized as the Sten, a British submachine gun used during World War II. The Sten was designed in 1940 and was mass-produced from 1941 to 1945. It was a simple and inexpensive weapon that was easy to manufacture and maintain, making it an ideal choice for the British military. The Sten was used by British and Commonwealth forces throughout the war and was also supplied to resistance groups in occupied countries.