Complex sentence: It is at this point that Blume became known for his initiatives in the persecution of Jews by calling the attention of his superiors, who in 1939 appointed him Director of Staff of the Gestapo.
Split into simpler sentences: It is at this point Blume became known for his initiatives in the persecution of Jews. Gaining the attention of his superiors, in 1939 he was appointed the Director of Staff of the Gestapo.