Complex sentence: On May 22,1856, Brooks beat Senator Charles Sumner with his Gutta-percha wood walking cane in the Senate chamber because of a speech Sumner had made three days earlier, for singling out Brooks' relative, Andrew Butler.
Split into simpler sentences: On May 22,1856, Brooks beat Senator Charles Sumner with his Gutta-percha wood walking cane in the Senate chamber. The cause was a speech Sumner had made three days earlier, in which he had singled out a relative of Brooks, Senator Andrew Butler.