Invasion of Yugoslavia
During the Invasion of Yugoslavia of April 1941, III./JG 52 was kept back in reserve to guard the Ploiești oil installations. On 15 May, III./JG 52 was moved to Athens and together with other "Luftwaffe" units, flews its first combat missions in support of the Battle of Crete. During this campaign, Steinbatz flew multiple ground support missions against Greek forces and other Allied forces.