Complex sentence: He was mustered into service on May 6,1898 served with the batter in Puerto Rico, returned to the United States and was mustered out with the battery on November 9,1898.
Split into simpler sentences: He was mustered into service on May 6,1898 and served with the battery in Puerto Rico. He returned to the United States and was mustered out with the battery on November 9,1898.