Complex sentence: Early in the Pacific Campaign of World War Two he was the head of the Naval Aviation Development Division in the Munitions Ministry and was responsible for some of the technical details of the attack on Pearl Harbor in 1941, under command of Admiral Isoroku Yamamoto.
Split into simpler sentences: Early in the Pacific Campaign of World War Two he was head of the Naval Aviation Development Division in the Munitions Ministry. He was responsible for some of the technical details of the attack on Pearl Harbor in 1941, under command of Admiral Isoroku Yamamoto.