In late April Colonel Merchant’s Marines joined with VNAF and U.S. Army elements to launch what would be the costliest and most viciously opposed heliborne assault attempted in South Vietnam during the 1962–1965 period. On the 26th, Merchant, Lieutenant Colonel La Voy, and Lieutenant Colonel George Brigham, the task element operations officer, flew to Quang Ngai and Pleiku to participate in the final stages of planning for a multi-battalion heliborne offensive into the Do Xa area, the mountainous Viet Cong stronghold located along the northern border of II Corps. At Quang Ngai officials from the II Corps headquarters had already completed the general plans for Operation SURE WIND 202 (Vietnamese code name: QUYET THANG 202), the size of which demanded the use of all transport helicopters available in both I and II Corps. The Marine representatives learned that HMM-364’s role in the upcoming operation would be to helilift a 420-man South Vietnamese battalion from the Quang Ngai airfield to Landing Zone BRAVO, an objective located about 30 miles due west of the pickup point. Simultaneous with this assault, a U.S. Army helicopter company based at Pleiku was scheduled to transport two ARVN battalions (960 troops) from Gi Lang, an outpost located 24 miles west-southwest of Quang Ngai, to a second landing zone about eight miles west-southwest of Landing Zone BRAVO. The operation was to begin on the morning of 27 April, with the first assault waves scheduled to land at 0930. Due to the distance between the mountainous landing zones and because two different helicopter units would be conducting the respective trooplifts, the operation plan treated the two assaults as separate operations. A U.S. Air Force U-10 aircraft had been assigned to carry Colonel Merchant, the TACA, and other ASOC representatives who would coordinate the helilift into Landing Zone BRAVO. Twenty Vietnamese A-1H Skyraiders had been assigned to provide tactical air support for the Marine portion of the operation. Twelve of these attack aircraft were scheduled to conduct preparatory strikes on and around the landing zones, four were to orbit above the area after the helicopter landing began, and the remaining four were to be positioned on airstrip alert at Da Nang. Five Army UH-1B gunships were assigned to escort the Marine UH-34Ds to and from the landing zone.