Complex sentence: After completing his education he became a bookkeeper in a bank managed by one of his relatives, and at age 21 he gained employment at a bank in Bridgeport, Connecticut, the hometown of his wife Kate Trubee.
Split into simpler sentences: After completing his education, he worked as a bookkeeper in a bank managed by a relative. At age 21, he switched to working at a bank in Bridgeport, Connecticut, the home of his wife Kate Trubee.