Complex sentence: After college, Green joined the United States Army and served at various times with the 82nd Airborne Division, the 25th Infantry Division, and the 2nd Infantry Division, where he commanded the 2nd Airborne Battalion.
Split into simpler sentences: After college, Green joined the United States Army. During his time in the army, Green served at various times with the 82nd Airborne Division, the 25th Infantry Division, and the 2nd Infantry Division, where he commanded the 2nd Airborne Battalion.