The Aerosan (Russian for "Aero-Sleigh" or propeller-driven sleigh) is a very specific form of military vehicle that was used operationally in snowbound winter regions of northern Europe by the armies of several countries during the first half of the 20th century. It was, however, the Soviet Union that made the most extensive military use of these specialised winter combat vehicles. Aerosans were used by Russian forces during the First World War, the Civil War following the 1917 Russian Revolution, by the Red Army during the Russo-Finnish "Winter War" of 1939-40, and in the winter months of the Second World War on the Eastern Front. Aerosans proved particularly effective in the combination of snowbound northern climate and poor road infrastructure that afflicted the Soviet Union, where tracked as well as wheeled vehicles were frequently confined to roads by heavy snowfalls.This publication covers the Soviet development of the aerosans from the early 20th century to the end of World War 2. Added are chapters of aerosans in Finnish Army and German Wehrmacht service, both of Soviet design and domestic developments.