The airstrip, which became known as LZ Stud, had to be ready well before D-day (1 April 1968). It became evident during the planning that the construction of an airstrip in the vicinity of Ca Lu would be a key factor for the entire operation. To accomplish the mission, the 1st Cavalry Division was augmented by the non-divisional units of the 1st Marine Regiment, 26th Marine Regiment, III Army of the Republic of Vietnam Airborne Task Force and the 37th Army of the Republic of Vietnam Ranger Battalion. On 11 March 1968, at the request of the Marine Command, the 1st Cavalry Division began a detailed plan, Operation PEGASUS, designed to relieve the Marines at Khe Sanh.
The North Vietnamese had ringed the lines of the Marines with a buildup of entrenched infantry and a multitude of antiaircraft weapons. Throughout the weeks that the 1st Cavalry Division was engaged in the Tet Offensive, the 26th Marines at Khe Sanh were besieged by heavy artillery bombardment and ground attack. Operation Pegasus The 26th Marines at Khe Sanh were besieged by heavy artillery bombardment and ground attack.
