The Soviet Union's Red Army raised divisions during the Russian Civil War, and again during the interwar period in 1926.Only a few of the Civil War divisions were retained in this period, and even fewer survived the reorganization of the Red Army during the 1937–1941 period. During the Second World War 400 'line' rifle divisions (infantry), 129 Soviet Guards rifle divisions, and over 50 cavalry divisions as well as many divisions of combat support arms were raised in addition to the hundreds of divisions that existed in the Red Army before Operation Barbarossa. Almost all the pre-war mechanized and tank divisions were disbanded during the war. There were also Red Air Force aviation divisions, and the NKVD divisions which also took part in fighting.