Complex sentence: He was assigned to the Marine Corps Recruit Depot Parris Island in South Carolina, and after completing recruit training in December, was transferred to Headquarters Company, Post Troop, and then to Provisional Company W, on January 17,1941.
Split into simpler sentences: He was assigned to the Marine Corps Recruit Depot Parris Island in South Carolina. He completing recruit training in December and was transferred to Headquarters Company, Post Troop and then to Provisional Company W at Parris Island, on January 17,1941.