Complex sentence: In addition, Leo Baeck was between 1943 to 1945 the speaker of the Council of Elders of Theresienstadt, after being deported from Berlin, where he had served as the head of the "Reichsvereinigung der Juden in Deutschland".
Split into simpler sentences: In addition, Leo Baeck was the speaker of the Council of Elders of Theresienstadt from 1943 to 1945. Before being deported from Berlin, he had served as the head of the "Reichsvereinigung der Juden in Deutschland".