Complex sentence: In August 1916, he vacated his position in the reserves to accept a Regular Army commission as a second lieutenant under the name Adolph Charles Weidenbach, he rose to Captain and served in World War I in the American Expeditionary Force.
Split into simpler sentences: In August 1916, he vacated his position in the reserves to accept a Regular Army commission as a second lieutenant under the name Adolph Charles Weidenbach. He rose to Captain and served in World War I in the American Expeditionary Force.