mm Parabellum while others were used unmodified (the German 7.63×25mm Mauser cartridge had identical dimensions to the 7.62×25mm Tokarev, albeit slightly less powerful). During the Winter War, the badly outnumbered Finnish used the Suomi KP/-31 in large numbers against the Russians with devastating effect. Finnish ski troops became known for appearing out of the woods on one side of a road, raking Soviet columns with SMG fire and disappearing back into the woods on the other side. During the Continuation War, the Finnish Sissi patrols often equipped every soldier with KP/-31s. The Suomi fired 9 mm Parabellum ammunition from a 71-round drum magazine (although often loaded with 74 rounds). "This SMG showed the world the importance of the submachine gun in modern warfare", prompting the development, adoption and mass production of submachine guns by most of the world's armies. The Suomi was used in combat until the end of the Lapland war, was widely exported and remained in service to the late 1970s. Inspired by captured examples of the Soviet PPS submachine gun, a gun that was cheaper and quicker to manufacture than the Suomi, the Finns introduced the KP m/44 submachine gun in 1944. In 1940, the Soviets introduced the 7.62×25mm PPD-40 and later the more easily manufactured PPSh-41 in response to their experience during the Winter War against Finland. The PPSh's 71-round drum magazine is a copy of the Suomi's. Later in the war they developed the even more readily mass-produced PPS submachine gun - all firing the same small-caliber but high-powered Tokarev cartridges. The USSR went on to make over 6 million PPSh-41s and 2 million PPS-43s by the end of World War II. Thus, the Soviet Union could field huge numbers of submachine guns against the Wehrmacht, with whole infantry battalions being armed with little else. Even in the hands of conscripts with minimal training, the volume of fire produced by massed submachine guns could be overwhelming. Britain entered the war with no domestic submachine gun design but instead imported the expensive US M1928 Thompson. After evaluating their battlefield experience in the Battle of France and losing many weapons in the Dunkirk evacuation, the Royal Navy adopted the 9 mm Parabellum Lanchester submachine gun. With no time for the usual research and development for a new weapon, it was decided to make a direct copy of the German MP 28. Like other early submachine guns it