The spring of 1964 saw a new, substantially larger Marine communications detachment introduced into the northern provinces of South Vietnam. Unlike its predecessors at Pleiku and Phu Bai, this unit was composed exclusively of Marines and included an infantry element for security purposes. Designated the Signal Engineering Survey Unit, the radio detachment consisted of three officers and 27 enlisted men drawn from the 1st Radio Company, FMFPac, and from Headquarters Marine Corps. This element, commanded by Major Alfred M. Gray, Jr. arrived at Da Nang on 20 May along with a 76-man infantry detachment from Company G, 2d Battalion, 3d Marines. The infantry element, reinforced with an 81mm mortar section (two mortars), was commanded by First Lieutenant Raymond J. Otlowski. Major Gray assumed overall command of the composite force which was designated Marine Detachment, Advisory Team One. Advisory Team One became the first actual Marine ground unit to conduct independent operations in the Republic of Vietnam. U.S. Air Force C-123 transports airlifted the bulk of the newly formed unit to the Civilian Irregular Defense Group (CIDG) camp at Khe Sanh in northwestern Quang Tri Province in the closing days of May. Two officers and five enlisted communicators remained behind at Da Nang and a four-man team positioned itself in the U.S. Army compound at Phu Bai to provide radio support for the main body. At Khe Sanh, Advisory Team One initially concentrated on building a solid supply base prior to undertaking actual communications operations. ARVN truck convoys brought the preponderance of its supplies from Quang Tri over Route 9, the old colonial road that snaked through the Annamite Mountains into Laos. While Major Gray and his men proceeded with this task, Marine UH-34Ds from Da Nang helilifted an ARVN infantry company onto Tiger Tooth Mountain (Dong Voi Mep), a jungle-covered mountain located eight miles north of the CIDG Camp. With an elevation of 5,500 feet, Tiger Tooth Mountain is the highest terrain feature in northern I Corps. On 13 June U.S. Army UH-1B helicopters lifted Major Gray, nine enlisted men, and several thousand pounds of equipment into a tiny landing zone which the South Vietnamese troops had hacked out near the top of the rugged mountain. The ARVN soldiers, who had established a rough perimeter around a peak slightly below the mountain’s highest point, were on hand to greet the small group of Americans. After the initial helilift, however, bad weather in the form of dense clouds intervened to delay the remainder of the movement for an entire week. SHUFLY helicopters finally completed the mission on 21 June. When the helilift concluded 73 Marines and roughly 100 Vietnamese troops were strung around and across a 5,000-foot peak just south of Tiger Tooth’s highest elevation. Another 81 Leathernecks remained at Khe Sanh to provide a pool from which fresh security forces and radiomen could be drawn when needed.