The First Cavalry Division (Airmobile) was selected by U.S. Commander William Westmoreland to carry out the operation. The 1st Cavalry had borne the brunt of the combat during the Siege of Plei Me and the Battle of Ia Drang in October and November 1965, and some battalions of the 1st Cavalry had sustained heavy casualties. More than 5,000 soldiers in the division were recent arrivals in Vietnam with little combat experience. The South Vietnamese 22nd Division stationed in Binh Dinh had also suffered heavy casualties in recent fighting and was on the defensive.