Complex sentence: In 1938 he went up to Balliol College, Oxford, to read Geography, but left after 4 terms to join the RNVR, serving as a Lieutenant in command of Motor Gun Boats operating out of Felixstowe.
Split into simpler sentences: In 1938 he went up to Balliol College, Oxford, to read Geography, but left after four terms to join the RNVR. James served as a Lieutenant in command of Motor Gun Boats operating out of Felixstowe.