Complex sentence: From 1897 to 1899, Harrison was an instructor in the New York Night Law School he later left to serve in U.S. Army during the Spanish-American War, first as a captain and later as an assistant adjutant general.
Split into simpler sentences: From 1897 to 1899, Harrison was an instructor in the New York Night Law School. He later left to serve in U.S. Army during the Spanish-American War, first as a captain and later as an assistant adjutant general.