Entering service in 1931, the 9x19mm Suomi KP/-31 submachine gun saw extensive combat with Finnish troops during their fight against Soviet forces in 1939-44. It was also manufactured under licence in Switzerland, Denmark and Sweden, and remained in Finnish service until the 1980s, an indication of its durability.

Rugged and accurate, the Suomi was a favourite with Finnish ski troops who would strike from ambush, cutting down Soviet troops, then skiing away into the woods. Initially used by the Finns as a light machine gun at infantry squad level, it eventually became a dedicated submachine gun, and since it had been designed to be more accurate than the typical SMG, it was often even used as a sniping weapon, or to supplement longer-ranged rifles such as the Mosin-Nagant. Featuring first-hand accounts and specially commissioned colour artwork, this is the story of one of World War II's most distinctive and respected infantry weapons.