The submachine-gun is a compact automatic weapon firing pistol ammunition, designed for short-range assault and close-quarter fighting.

In the early stages of the Second World War the British Army purchased the Tommy Gun from the United States. These were expensive and in 1941 they switched to the Sten Gun made in Enfield. It was named after the combined first letters of the names of the designers, R. V. Shepherd and H. J. Turpin, and the Enfield Royal Small Arms Factory.

There were several models of the Sten Gun but the Mark 2 was the most popular. The gun had a massive bolt inside a tubular casing with the barrel fixed to the front and the magazine feeding from the left side where it could be supported on the firer's forearm.

During the Second World War the Royal Small Arms Factory supplied 4 million of these guns to the British Army. It was not popular with the soldiers because its habit of jamming when being used in battle. However, they were cheap to buy and the British government distributed them to resistance groups throughout occupied Europe. The gun could be easily and rapidly dismantled into its component parts for concealment, which was a distinct advantage for underground fighters.