Stalin's Red Army entered the Second World War as a relatively untried fighting force. In 1941, with the launch of Operation 'Barbarossa', it joined the battle with Hitler's army, the most powerful in history. After a desperate war of attrition over four years, the Red Army defeated the Nazis on the Eastern Front and won lasting fame and glory in 1945 by eclipsing the military might of the Third Reich. This book begins with a review of the historical background of the Red Army in the years leading up to the outbreak of war in 1939, followed by a discussion of the major themes in the development of Soviet forces during the 'Great Patriotic War' that ensued in 1941. The Red Army's organisational structures are examined, from high command down to divisional level and below, which helps Western readers to understand the differences between the terminology of the Soviet and common Western (British, US and German) armies. Soviet combat arms - infantry, armour and mechanised forces, cavalry, airborne and special forces - are described, along with a technical overview of infantry weapons, armoured vehicles, artillery and support equipment. Fully illustrated with a comprehensive selection of archive photographs, charts and tables of organisation, this is an indispensable source of reference for anyone interested in the armies of the Second World War.