The 21st Mechanized Corps was a formation in the Soviet Red Army during the Second World War. Initially formed in March 1941, in response to the German victories in the West it was attached to the newly forming 27th Army, and held in reserve near Opochka in Soviet Union South of Pskov in the Special Baltic Military District. It was under the command of Major General Lelyushenko when the German Operation Barbarossa began in June 1941. It initially consisted of the 42nd and 46th Tank Divisions, and the 185th Mechanized Division. After the Invasion began the Special Baltic Military District was renamed Northwestern Front, Commanded by Colonel General Kutznetsov. The front fielded 8th and 11th Armies with the 27th Armies in its second echelon. The 21st Mechanized was heavily engaged in the fir