He continued his military career after the war in the Engineers, until he was selected in 1928 to participate in the secret pilot training programme in the Soviet Union.

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.

At the beginning of 1943 Korten was promoted to general and in the summer replaced Alfred Keller at Luftflotte 1 (1st Air Fleet).

Korten was seriously wounded in the Wolfsschanze near Rastenburg during the 20 July Plot in 1944, in which Colonel Claus von Stauffenberg attempted to assassinate Hitler with a bomb.