In 1962, the Geneva Accords declared Laos a neutral country in the fight for Vietnam. US and SEATO (South East Asia Treaty Organization, the Pacific’s NATO) pulled out immediately, but North Vietnam kept about 7000 troops in the north of the country to support the Pathet Lao, the Laotian Communist insurgents. Unwilling to accept the political costs of sending troops back into Laos, Kennedy and later Johnson supported the Royal Laotian government with cash, mercenaries, and covert support. The war in Laos became the purview of the CIA. The “Secret War in Laos” was the largest CIA covert operation of the Cold War until Afghanistan in the 80s.

In 1965, the monsoon disrupted US bombing campaigns against the Communists, specifically Operations Rolling Thunder in North Vietnam, Steel Tiger on the Ho Chi Minh Trail in the Laotian panhandle, and Barrel Roll against the Pathet Lao in northern Laos. So a navigational station was put on top of Phou Pha Thi, a jagged and steep mountain in the Hmong dominated area of Laos. The Hmong, like the Montagnards in Vietnam, were a tough mountain people who had been fighting Communists for a decade. A tactical navigational aid (TACAN) transponder was placed at Landing (Lima) Site 85 on the very top of Phou Pha Thi, a Hmong sacred mountain whose summit was thought to be impenetrable to anyone who hadn’t lived in the area their entire lives.

Lima Site 85 was just one of hundreds of landing sites for the CIA’s proprietary airline in Laos, Air America. Also, LS-85 was quickly discovered to be the perfect place for radar to cover the North Vietnamese heartland, and its height gave a straight shot to cover Hanoi and Haiphong, just 175 miles away to the east. The site was expanded but still small, just a landing pad, and three small buildings for commo, operations, and living quarters. However, the TSQ-81, a portable version of the venerable and reliable MSQ-77 radar, required a team of 12 US Air Force technicians to operate. This posed a problem: No US military personnel were allowed in the country. So the CIA “sheep-dipped” them. Sheep Dipping is the practice of asking for military volunteers for a covert mission, discharging them from the service, hiring them through a civilian company, in LS-85’s case Lockheed Aircraft Service Corp, and when the mission was over they releasing themd back into the service.

By the end of 1967, Lima Site 85 directed nearly a quarter of all US airstrikes in theater. The North Vietnamese knew of the site and in mid-1967 began a concerted effort to break into Hmong territory and seize Phou Pha Thi. By 1968, almost half of LS-85’s airstrikes were in support of Royal Laotian troops or CIA led Hmong militia. In January 1968, the first direct assault on LS-85 occurred when two North Vietnamese Antonov-2 Colt biplanes attempted to bomb the site. But the slow moving planes were shot down by Air America Huey crewmembers with small arms, a submachine gun in one case.

With the failure of their air attack, the North Vietnamese and Pathet Lao began ground operations against LS-85 in earnest. They were close enough to shell and rocket the site, but its position meant almost all of the incoming rounds either hit the side of the mountain or flew harmlessly overhead. Nonetheless, the indicators were ominous. The CIA brought in several companies of Hmong militia and a Thai Army infantry battalion that were under cover as “mercenaries” to defend the base of the mountain.

The Hmong were excellent guerrilla fighters but they were unsuited for a static defense against a deliberate attack by North Vietnamese regulars and a swarm of Pathet Lao. On 18 February 1968, a North Vietnamese officer was captured five miles south east of the site. On him were papers that indicated an imminent attack on the site by four battalions of the veteran 766th PAVN Regiment and one PL battalion, supported by a battalion of artillery. However, LS-85 was integral to the air campaign and would not be evacuated. The authority to evacuate rested solely with the American ambassador in the Laotian capital of Vientiane, and then only at the sole request of the Air Force. Furthermore, no more troops were brought in to defend the site as air power and the terrain were thought to be sufficient.

On 9 March, 1968, the Communists attacked. Despite massive American airstrikes, the North Vietnamese and Communist Laotians pushed the Hmong and Thai soldiers with their CIA commanders slowly up the mountain. Even during the attack, the Air Force did not want to request evacuation as the inclement weather in North Vietnam made the radar exceptionally valuable. But for the first time, they did issue the technicians M-16s, who up to this point had been unarmed because they were posing as civilians working for Lockheed. Only the senior NCO, CMSgt Richard Etchberger, knew how to competently operate the weapon. On 10 March, the fighting was dangerously close to the site, but even as late as 9pm the Air Force thought they could hold out. The ambassador authorized a dawn extraction by Air America for the technicians and the remaining Thai and Hmong soldiers. The CIA station chief immediately commented that it “was a day too late.”

The Air Force might have been correct, the Communists sustained significant casualties assaulting the mountain and looked to suspend attacks. But they were just waiting on their trump card – Communism is nothing if not dangerously seductive and a dozen local Hmong mountaineers volunteered to scale the northern cliff face to show their dedication to the cause. At 3 am on the morning of 11 March, the Hmong sappers attacked the compound from the rear. They killed several Air Force technicians in the barracks and surprised several more exiting the ops building fumbling with their weapons. The technicians weren’t ignorant of their precarious situation and knew they couldn’t rely on the ambassador and their own command for a timely evacuation. So they prepared ropes to rappel down the mountain to safety. The off-duty shift immediately did this, but the sappers killed them on the shelf below the cliff face. That any Americans survived the initial attack at all was due to Etchberg fighting from the commo building.

Upon hearing firing from the top of the mountain, the senior CIA commander, a former Green Beret Huey Marlow, took his Hmong radio man and trotted toward the site’s buildings. With his shotgun and some gratuitous close combat, he killed a sapper machine gun crew positioned to stop any counterattack from below, and scattered the remaining sappers. However, his missing presence from the fight at the base of the mountain was the final straw that broke the Hmong and Thai resistance from the unceasing Communist attacks.

After dawn Air America helicopters evacuated 8 of the 19 Americans on Lima Site 85, and as many Hmong and Thai soldiers as they could in four chaotic landing attempts. The last American brought off was the wounded TACAN technician Jack Starling, who had been playing dead underneath one of the buildings. At 9:46 am, nearly four hours after dawn and six after the sapper attack, an MH-53 Jolly Green Giant returned for him after a friend said he was probably still alive. Starling sprinted and jumped into the helicopter hovering off the cliff face while the door gunners returned fire against the multitude of Communists then at the site. Hollywood has nothing on reality.

Eight of the eleven remaining Americans were known to have been killed in the attack and three were initially thought captured. Later in the day, it was determined that they also were killed, and the Air Force bombed the hell out of the site to prevent the equipment from being analyzed by the Communists.

The surviving technicians of the Battle of Phou Pha Thi returned to Air Force service. Marlowe received an Intelligence Star for actions on the mountain during the night 10/11 March 1968. In 2003, a Joint POW/MIA Accounting Command expedition to Laos found the remains of one technician and the equipment of four more, whose bodies were thrown off the mountain by the North Vietnamese. CMSgt Etchberger’s widow (he was killed in the evacuation from ground fire that penetrated his helicopter’s floorboards) received a Medal of Honor from President Obama at a small White House ceremony in 2012.

The Fall of Lima Site 85 was a grievous blow to Operation Rolling Thunder. Without the TACAN and the radar, the bombing had to be severely curtailed during the monsoon season. Politically, ending the operation became more useful than any military effect it had when the monsoon arrived. President Johnson suspended Operation Rolling Thunder in May, 1968, and cancelled it completely in November.