On 22 June 1941, Operation Barbarossa began and German troops invaded the Soviet Union. On the first day of combat, the regiment lost 36 of its 66 aircraft to German bombing raids. However, the regiment reportedly downed 11 German aircraft while losing three more aircraft. Two of these victories were credited to Korobkov. On 25 June, he also shot down two Junkers Ju 88s. The regiment then fought in the Battle of Kiev. He was promoted to Lieutenant colonel on 10 October. Korobkov was awarded his second Order of Lenin on 5 November. On 26 December, the 12th IAP became the 486th Fighter Aviation Regiment. The regiment fought in the Battle of the Kerch Peninsula. In April, Korobkov became the deputy commander of the 47th Army air force. Korobkov was evacuated from Kerch after its loss in May and became the commander of the 16th Aviation Group Impact. In June, he became the commander of the 265th Fighter Aviation Division. In November, he became a senior inspector for Soviet Air Force Inspection. In February 1943, Korobkov returned to command of the 265th Fighter Aviation Division (IAD) and fought in the Battle of the Caucasus. On 28 May he was promoted to colonel. In June, he became the commander of the 320th Fighter Aviation Division of the 1st Fighter Air Army Defense Forces in Moscow.