The paper is concerned with the prerequisites of the creation of the labour armies during the Civil War in Soviet Russia (1917–1921), the main functions and results of these armies’ operations. The conclusion is made that labour armies were an imminent part of military communism, they never happened to be employed as the Red Army’s reserve but as a tool of militarizing the country’s economy and policies. The evolution of the organized labour units took two directions. Firstly, standardized units were being gradually organized instead of numerous and miscellaneous detachments that made the core of the labour armies in 1920. Another tendency consisted in reducing the number of excessive managerial staff that required additional resources. It is noted that the massive use of the armed forces for labour purposes is always a reaction to the critical situation in which a country finds itself, when neither political nor economic challenges can be responded to by standard means. Thus, the employment of militarized labour units at peacetime can never be justified. On the whole, labour armies proved effective as an emergency means of tackling economic problems and ensuring immediate economic operations. Despite the limited time span in which the labour armies had operated, they left a clear impact on the further course of events in Soviet Russia.