When Operation Barbarossa began in June 1941 Sukhomlin was named deputy chief of staff for the Northwestern Front centered around Leningrad. In September he was chosen as acting chief of staff for the 54th Army, part of the Leningrad Front. In January 1942 he briefly assumed command of the 8th Army on the Volkhov Front before taking command of the 54th Army, recovering from the Soviet loss in the Battle of Lyuban. He led the army in February 1943 during Operation Polar Star, an unsuccessful attempt to lift the blockade of Leningrad. His role was to attack toward Tosno and link up with the 55th Army attacking from Krasny Bor. Sukhomlin was demoted to deputy commander of the army for his failure. In March he was named assistant commander of the Volkhov Front and in June he became chief of staff of the 5th Army on the Western Front.