Steinbatz volunteered for military service in the Austrian Armed Forces in 1937. In March 1938, following the Anschluss, the annexation of Austria by Nazi Germany, Steinbatz was transferred to the Luftwaffe. Following flight training, he was posted to Jagdgeschwader 52 (JG 52—52nd Fighter Wing).
Steinbatz joined the Austrian military in 1937. Following Austria's takeover by Nazi Germany in March 1938, he was transferred to the Luftwaffe and received flight training before being assigned to a fighter squadron.