the German invasion of the Soviet Union. JG 51, under the command of Oberstleutnant Werner Mölders, was subordinated to II. Fliegerkorps (2nd Air Corps), which as part of Luftflotte 2 (Air Fleet 2). JG 51 area of operation during Operation Barbarossa was over the right flank of Army Group Center in the combat area of the 2nd Panzer Group as well as the 4th Army. On the first day of the invasion, Huppertz, who was flying with 12. Staffel commanded by Oberleutnant Karl-Gottfried Nordmann, claimed a Tupolev SB bomber shot down. The Gruppe was moved to an airfield at Schatalowka, present-day Shatalovo air base, southeast of Smolensk, on 21 July. Huppertz accounted for a Petlyakov Pe-2 bomber on 23 July. Three were lost from the 411 BAP (Bombardirovochnyy Aviatsionyy Polk—bomber aviation regiment) operating under the OSNAZ (Osoboye Naznachenie—Special purpose-unit or task force). German pilots submitted three claims. On 9 August, Huppertz was shot down in his Bf 109 F-2 (Werknummer 8938) near Schatalowka. He was shot down by the air gunner Serzhant Listratow from the 57 BAP. That day, he had claimed two aerial victories when he shot down a Polikarpov I-16 fighter and a SB-3 bomber. Huppertz was then transferred to 9. Staffel of JG 51 where he claimed his last aerial victory on the Eastern Front on 25 August over an I-16 fighter, taking his total to 34 aerial victories. At the time, 9. Staffel was commanded by Oberleutnant Karl-Heinz Schnell. Huppertz was awarded the Knight's Cross of the Iron Cross () on 30 August 1941. Squadron leader In September 1941, Huppertz was appointed Staffelkapitän (squadron leader) of 1. Staffel of the Ergänzungsgruppe of JG 51, a supplementary training group. At the time, the unit was based in Zerbst before moving to Düsseldorf and to Vannes-Meucon Airfield in mid October. In January 1942, the Staffel became part of the newly formed IV. Gruppe of Jagdgeschwader 1 (JG 1—1st Fighter Wing) where it thus became 12. Staffel of JG 1. IV. Gruppe first major task was Operation Donnerkeil, an air superiority operation to support the Kriegsmarine (German Navy) Operation Cerberus. The objective of this assignment was to give the German battleships and and the heavy cruiser fighter protection in the breakout from Brest to Germany. During this operation, Huppertz claimed a Spitfire fighter shot down on 12 February. End-February to early March 1942, IV. Gruppe began relocating north to