Complex sentence: After serving in World War I, in France, Vrest entered the class of 1923 at Harvard and then served briefly in the U.S. Consular Service before moving to New York City in 1925.
Split into simpler sentences: After serving in World War I, in France, Vrest entered the class of 1923 at Harvard. He served briefly in the U.S. Consular Service before moving to New York City in 1925.