Complex sentence: There was a Japanese military base on Chichijima, whose officer in charge, Major, was known for performing cannibalism and other acts on prisoners of war and was executed for his crimes after the war.
Split into simpler sentences: There was a Japanese military base on Chichijima, whose officer in charge, Major, was known for performing cannibalism and other acts on prisoners of war. He was executed for his crimes after the war.