Complex sentence: Beginning life as Claus Cecil Borberg, Bülow was the son of Danish playwright Svend Borberg (1888--1947), who was regarded as a Nazi collaborator for his activities during the Second World War in the German occupation of Denmark.
Split into simpler sentences: Beginning life as Claus Cecil Borberg, Bülow was the son of Danish playwright Svend Borberg (1888--1947). His father was regarded as a Nazi collaborator for his activities during the Second World War in the German occupation of Denmark.