Complex sentence: The original unit to take control of the base was 1-10th Cavalry of the 4th Infantry Division and was handed over to 4th Aviation Brigade of the 4th Infantry Division in the 2nd week of the war.
Split into simpler sentences: The original unit to take control of the base was 1-10th Cavalry of the 4th Infantry Division. The base was then handed over to the 4th Aviation Brigade of the 4th Infantry Division in the second week of the war.