Complex sentence: Returning from the Army, Doppmann had the responsibility of taking care of his children and his wife, and later became a professor in three major universities in Washington, and was a composer for the next 12 years.
Split into simpler sentences: Returning from the Army, Doppmann took care of his children and his wife. He became a professor in three major universities in Washington, and was a composer for the next 12 years.