World War II in Europe had begun on Friday 1 September 1939 when German forces invaded Poland. In January 1943, Obleser arrived with 8. "Staffel" under command of "Hauptmann" Günther Rall at the Gigant airfield which was located in the vicinity of Salsk. At the time, the Red Army had launched Operation Koltso, the final phase of the Battle of Stalingrad. Rall made Obleser his wingman and also appointed him as technical officer of the "Staffel", a position which was responsible for the overall readiness of the equipment and aircraft. Obleser flew his first combat mission on 12 January 1943 on the Eastern Front. There, he claimed his first aerial victory on 28 March over a Bell P-39 Airacobra. On 28 May 1943, Obleser was wounded when his Messerschmitt Bf 109 G-4 ("Werknummer" 19284—factory number) was hit by anti-aircraft artillery resulting in a forced landing at Varenikovskaya. Following his convalescence, he was appointed "Staffelkapitän" (squadron leader) of 8./JG 52 on 6 July 1943.