Complex sentence: On March 15,1938, he was transfered to the Luftwaffe and was made Commander of the Luftwaffe in Austria, by this time he had been promoted to Generalleutnant.
Split into simpler sentences: On March 15,1938, he was transfered to the Luftwaffe and where he was made Commander of the Luftwaffe in Austria. By this time he had been promoted to Generalleutnant.