sentences:  The entire Airborne Division arrived in late May and was given responsibility for a sector between the Division and the 1st Division.The 1st Marine Division then assumed control of the 1st Ranger Group which had just arrived from Da Nang.On 13 May 2 battalions of the 369th Brigade launched a heliborne assault on helicopters of the US 9th Marine Amphibious Brigade (9th MAB) against PAVN positions in the Hải Lăng District southeast of Quảng Trị, sweeping the area before returning to the My Chanh line.