Complex sentence: He served as a naval bomb safety officer during the Normandy Landings of June 1944, defusing many bombs, mines and shells, before clearing mines in the river Scheldt and habour basins in September of that year.
Split into simpler sentences: He served as a naval bomb safety officer during the Normandy landings of June 1944, defusing many bombs, mines, and shells. He cleared mines in the river Scheldt and various harbour basins in September of that year.