Red Army

Its predecessor was the Red Guard, the armed workers' militia of 1917, which played the main part in the October coup. The new army's volunteer units proved too weak against the German offensive of February 1918. The real builder of the army was Leon Trotsky, commissar for military affairs from the spring of 1918. The Bolsheviks introduced conscription and took tens of thousands of former tsarist officers into service as "military specialists", watched over by political commissars; their families were often held answerable for their loyalty.

The Red Army fought the Whites, the Czechoslovak Legion and the Allied intervention forces, and in 1919–1920 the Polish Army. By the end of 1920 it numbered, by various estimates, between 5 and over 6 million men, though only a small part of them fought at the front. 23 February was later celebrated as its anniversary.