Complex sentence: Abendroth claimed to the Communist authorities in East Germany that he had never attended any political meeting, and his fortune would change at Thuringia, whose government appointed Abendroth for music director of Weimar from 1945 to 1956.
Split into simpler sentences: Abendroth claimed to the Communist authorities in East Germany that he had never attended any political meeting. The break would occur at Thuringia, whose government appointed Abendroth for music director of Weimar from 1945 to 1956.