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.
While the Imperial Russian Army was being taken apart, "it became apparent that the rag-tag Red Guard units and elements of the imperial army who had gone over the side of the Bolsheviks were quite inadequate to the task of defending the new government against external foes." Therefore, the Council of People's Commissars decided to form the Red Army on 28 January 1918. They envisioned a body "formed from the class-conscious and best elements of the working classes." All citizens of the Russian republic aged 18 or older were eligible. Its role being the defense "of the Soviet authority, the creation of a basis for the transformation of the standing army into a force deriving its strength from a nation in arms, and, furthermore, the creation of a basis for the support of the coming Socialist Revolution in Europe." Enlistment was conditional upon "guarantees being given by a military or civil committee functioning within the territory of the Soviet Power, or by party or trade union committees or, in extreme cases, by two persons belonging to one of the above organizations." In the event of an entire unit wanting to join the Red Army, a "collective guarantee and the affirmative vote of all its members would be necessary." Because the Red Army was composed mainly of peasants, the families of those who served were guaranteed rations and assistance with farm work. Some peasants who remained at home yearned to join the Army; men, along with some women, flooded the recruitment centres. If they were turned away they would collect scrap metal and prepare care-packages. In some cases the money they earned would go towards tanks for the Army.
The Council of People's Commissars appointed itself the supreme head of the Red Army, delegating command and administration of the army to the Commissariat for Military Affairs and the Special All-Russian College within this commissariat. Nikolai Krylenko was the supreme commander-in-chief, with Aleksandr Myasnikyan as deputy. Nikolai Podvoisky became the commissar for war, Pavel Dybenko, commissar for the fleet. Proshyan, Samoisky, Steinberg were also specified as people's commissars as well as Vladimir Bonch-Bruyevich from the Bureau of Commissars. At a joint meeting of Bolsheviks and Left Socialist-Revolutionaries, held on 22 February 1918, Krylenko remarked: "We have no army. The demoralized soldiers are fleeing, panic-stricken, as soon as they see a German helmet appear on the horizon, abandoning their artillery, convoys and all war material to the triumphantly advancing enemy. The Red Guard units are brushed aside like flies. We have no power to stay the enemy; only an immediate signing of the peace treaty will save us from destruction."
The Russian Civil War (1917–1923) occurred in three periods:
At the war's start, the Red Army consisted of 299 infantry regiments. Civil war intensified after Lenin dissolved the Russian Constituent Assembly (5–6 January 1918) and the Soviet government signed the Treaty of Brest-Litovsk (3 March 1918), removing Russia from the Great War. Free from international war, the Red Army confronted an internecine war against a loose alliance of anti-Communist forces, comprising the Revolutionary Insurrectionary Army of Ukraine, the "Black Army" led by Nestor Makhno, the anti-White and anti-Red Green armies, and others. 23 February 1918, "Red Army Day", has a two-fold historical significance: the first day of drafting recruits (in Petrograd and Moscow); and the first day of combat against the occupying Imperial German Army.
On 6 September 1918 the Bolshevik militias consolidated under the supreme command of the Revolutionary Military Council of the Republic – Russian: Революционну Военну Совет, translit. Revolyutsionny Voyenny Sovyet (Revvoyensoviet). The first Chairman was Leon Trotsky. The first commander-in-chief was Jukums Vācietis from the Latvian Riflemen; in July 1919 he was replaced by Sergey Kamenev. Soon afterwards Trotsky established the GRU (military intelligence) to provide political and military intelligence to Red Army commanders. Trotsky founded the Red Army with an initial Red Guard organization, and a core soldiery of Red Guard militiamen and Chekist secret police. Conscription began in June 1918, and opposition to it was violently suppressed. To control the multi-ethnic and multi-cultural Red Army soldiery, the Cheka operated special punitive brigades which suppressed anti-communists, deserters, and "enemies of the state". Wartime pragmatism allowed the recruitment of ex-Tsarist officers and sergeants (non-commissioned officers, NCOs) into the Red Army. Lev Glezarov's special commission recruited and screened them. By mid-August 1920 the Red Army's former Tsarist personnel included 48,000 officers, 10,300 administrators, and 214,000 NCOs. At the civil war's start, ex-Tsarists made up 75% of the Red Army officer-corps, who were employed as military specialists (voenspetsy, ru:Военный советник). The Bolsheviks occasionally enforced the loyalty of such recruits by holding their families as hostages. At war's end in 1922, ex-Tsarists constituted 83% of the Red Army's divisional and corps commanders.