This campaign was 8 March to 24 December 1965. During this campaign the U.S. objective was to hold off the enemy while gaining time needed to build base camps and logistical facilities. The U.S. also attempted to consolidate its ground operations more efficiently. For this purpose, it organized the U.S. Army Vietnam (USARV). U.S. support in the I Corps tactical zone, composed of five northernmost provinces, was to be primarily a Marine Corps responsibility; the U.S. Army was to operate mainly in the II and III Corps tactical zones which comprised the Central highlands, adjacent coastal regions, and the area around Saigon; and ARVN troops were to retain primary responsibility for the Delta region of the IV Corps.
On 19 October 1965. three VC regiments totaling 6,000 men attacked a Civil Irregular Defense Group (CIDG) - U.S. Special Forces at Plei Me, near the entrance to the Ia Drang Valley, in what purported to be the start of a thrust to cut the country in half.
With the assistance of massive air strikes, elements of the newly arrived 1st Cavalry Division thwarted the enemy in a battle that lasted nearly a month and included several engagements. The Ia Drang Valley action was the costliest in terms of casualties to date. The successful defense of the region improved security in and around the Central Highlands and raised the morale of the soldiers involved.