The Workers' and Peasants' Red Army (Russian: Рабоче-крестьянская Красная армия; РККА, or Raboche-krest'yanskaya Krasnaya armiya: RKKA, frequently shortened in Russian to Красная aрмия; KA, in English: Red Army also in critical literature and folklore of that epoch – Red Horde, Army of Work) was the army and the air force of the Russian Soviet Federative Socialist Republic, and after 1922 the Union of Soviet Socialist Republics. The army was established immediately after the 1917 October Revolution (Red October or Bolshevik Revolution). The Bolsheviks raised an army to oppose the military confederations (especially the various groups collectively known as the White Army) of their adversaries during the Russian Civil War. Beginning in February 1946, the Red Army, along with the Soviet Navy, embodied the main component of the Soviet Armed Forces; taking the official name of "Soviet Army" (Russian: Советская Армия (СА)/Sovetskaya Armiya), until its dissolution in December 1991.
The Red Army is credited as being the decisive land force in the Allied victory in the European theatre of World War II. During operations on the Eastern Front, it fought 75%–80% of the German land forces (Wehrmacht Heer and Waffen-SS) deployed in the war, inflicting the vast majority of all German losses and ultimately capturing the German capital.
In September 1917, Vladimir Lenin wrote: "There is only one way to prevent the restoration of the police, and that is to create a people's militia and to fuse it with the army (the standing army to be replaced by the arming of the entire people)." At the time, the Imperial Russian Army had started to collapse. Approximately 23% (about 19 million) of the male population of the Russian Empire were mobilized; however, most of them were not equipped with any weapons and had support roles such as maintaining the lines of communication and the base areas. The Tsarist general Nikolay Dukhonin estimated that there had been 2 million deserters, 1.8 million dead, 5 million wounded and 2 million prisoners. He estimated the remaining troops as numbering 10 million.