Complex sentence: He was hospitalized briefly from injuries sustained in Bougainville and then joined the 1st Marine Division in time for landings on Pelelieu and, later, Okinawa, where he was again wounded in action.
Split into simpler sentences: He was hospitalized briefly from injuries sustained in Bougainville. He then joined the 1st Marine Division in time for landings on Pelelieu and, later, Okinawa, where he was again wounded in action.