This study explores the organization, history and uniforms of the Soviet Red Army during the 20 years between its victory in the Civil War and the invasion of the USSR by Germany in 1941.The two decades following the Bolshevik victory over the 'Whites' in the Russian Civil War saw widespread and fundamental developments for the Red Army. Nevertheless, these still left it largely unready to face Germany's Operation Barbarossa in June 1941, having been reduced in size and planning for modernization.Despite Stalin's murderous purges of the officer class in the 1930s, the Red Army was victorious in clashes against Imperial Japan in 1938-39 and fighting for the Republicans in the Spanish Civil War (1936-39). Yet, shortly after taking over half of Poland in 1939, Stalin's 'Winter War' against Finland demonstrated serious inadequacies in the Red Army's readiness for modern warfare. This would be shockingly confirmed in the first days of Operation Barbarossa.Using rare photos and detailed colour artwork, this study explores the interwar history of the Red Army, describing its campaigns, organization and uniforms, and focusing on the 20 years between its victory in the Civil War and the invasion of the USSR by Germany in 1941.