Complex sentence: In addition to his involvement with the Society of the Cincinnati, Gardiner was one of the founders of the New York Society of the Sons of the Revolution in 1876 and served as commandant of the Veteran Corps of Artillery from 1908 to his death in 1919.
Split into simpler sentences: In addition to his involvement with the Society of the Cincinnati, Gardiner was one of the founders of the New York Society of the Sons of the Revolution in 1876. He also served as commandant of the Veteran Corps of Artillery from 1908 to his death in 1919.