 On 19 July he was promoted to Major-General.In January 1941 he transferred back to the 4th Air Fleet, in order to participate in the Balkans Campaign and in the assault on the Soviet Union (Operation Barbarossa).In August 1942 he was promoted to Lieutenant-General and took over the command over the "I. Fliegerkorps", which fought at the southern sector of the Eastern Front and was temporarily transferred to the ""Luftwaffenkommando Don"" during the Battle of Stalingrad.