II in Europe began on Friday 1 September 1939 when German forces invaded Poland. Wandel was appointed Staffelkapitän (squadron leader) of 2. Staffel of JG 76 on 1 March 1940. He succeeded Oberleutnant Anton Mader who was transferred. In April 1940, I. Gruppe moved to an airfield at Mainz-Finthen, originally named Fliegerhorst Ober-Olm. The Gruppe stayed at Ober-Olm until the Battle of France began. On 5 June 1940, Wandel claimed his first aerial victory when he shot down a Morane-Saulnier M.S.406 fighter near Amiens. He claimed one further victory before the Armistice of 22 June 1940, a Hawker Hurricane fighter shot down south of Dieppe on 7 June. The Hurricane possibly belonged to the Royal Air Force No. 43 or No. 601 Squadron. On 26 June 1940, I. Gruppe of JG 76 was moved to the airfield at Waalhaven in the Netherlands and subordinated to Jagdgeschwader 54 (JG 54—54th Fighter Wing). There, the Gruppe was tasked with providing aerial protection over the Dutch coastal area. On 5 July, I./JG 76 was officially integrated into JG 54 and was renamed to II./JG 54 and 2./JG 76 became 5./JG 54. On 31 July 1940, Wandel was transferred to the Jagdfliegerschule (fighter pilot school) at Zerbst. As a result, command of 5. Staffel was passed on to Oberleutnant Roloff von Aspern. War against the Soviet Union Wandel returned to JG 54 in late 1941 where he served as an adjutant to the Gruppenstab (headquarters unit) of II. Gruppe. At the time, II. Gruppe was commanded by Hauptmann Dietrich Hrabak. The Wehrmacht had launched Operation Barbarossa, the invasion of the Soviet Union, on 22 June with II. Gruppe supporting Army Group North in its strategic goal towards Leningrad. In early November, the Gruppe had been withdrawn from the Eastern Front for a period of rest and replenishment where they were based at airfields in Döberitz, and later at Uetersen. On 20 January 1942, the Gruppe began relocating to the Eastern Front where they would be based at Siverskaya near Leningrad. Flying missions over the Volkhov, Wandel claimed his first aerial victory on the Eastern Front over a Polikarpov I-16 fighter on 10 February. Operating from Siverskaya during the Battle of Lyuban, Wandel claimed eight further aerial victories. On 27 February, he shot down an I-18 fighter, an early German designation for a Mikoyan-Gurevich MiG-1 fighter. Wandel then claimed a Petlyakov Pe-2 bomber on on