January 12, 1968: High above the Laotian jungle, the 2 Antonov An-2 Colt biplanes banked to begin another run over the target. 120mm mortar shells fell from their bellies as rockets fired from wings, hoping to hit the small collection of buildings perched on the rocky ledge of a large mountain. The structures looked as out of place in this part of the world as the ancient aircraft sputtering back and forth above them seeking their destruction.

Then a helicopter appeared. An unmarked UH1 Huey. The planes broke off the attack and tried to flee. Their speed was no match for the Huey who easily caught them. A crewman leaned out the choppers open cargo bay firing an AK47 into the top of a Colt. It rolled over spewing smoke and plunged into the hills.

The chopper raced for another able to catch it quite easily and again the AK barked and the plane began its death plunge, its impact rolling a bright orange and black cloud high over the still jungle.

Back at the mountain top, the occupants dusted themselves off, tended their casualties, inspected the compound, and went back to work, having just survived the one of the most bizarre air attacks of the 3 year old American involvement in the Vietnam War.

No matter though, since the most important part of the mountain top outpost remained functioning: The TSQ-81 Tactical Air and Navigation radar (TACAN) that guided American strike aircraft to precise bomb release points in all-weather day and night over North Vietnam.

Known to few outside of those stationed there, the facility was called Lima Site 85.

One of the most closely guarded secrets of the war, the site was built on an outcropping of a 5,600 foot high mountain in Northeast Laos named Phou Pha Thi.

Origins of the facility began in summer 1966 when an earlier TACAN system was emplaced along with support personnel rotating every 2 weeks. The site was located just 15 miles from the North Vietnamese border and was dependent on weekly CIA helicopter flights to sustain it.

The Air Force technicians who ran the facility were required to wear civilian clothes because the U.S. was bound by a 1962 treaty forbidding foreign forces on Laotian soil. In fact, the personnel had to sign a form that temporarily released them from military service as long as they were in Laos.

In 1967, the site received the more advanced TSQ-81 radar and began functioning in November 1967 under the name Operation Commando Club with 19 personnel assigned.

From their consoles in the small olive drab buildings, controllers guided strike aircraft against targets that otherwise remained untouched due to weather. Successful sorties increased each month the radar operated, and by the end of 1967, was directing 55 percent of all bombing missions into North Vietnam.

All was not well behind the scenes; however, as reconnaissance aircraft showed the North Vietnamese building roads detached from main routes into the valley toward Phou Pha Thi.

Despite U.S. Ambassador to Laos William Sullivan desiring no personnel at the facility be armed, Major Richard Secord, in charge of security for the place, managed to obtain M16’s grenades Claymore mines and explosives to place on the radar in case the site was ever in danger of being captured. These measures provided the only security in the unlikely event the enemy ever came over the top.

Down in the lower part of the mountain and in the valley below, there was additional safety provided by CIA backed Laotian Hmong forces, though privately it was believed they would be unable to hold off a large sustained attack should one occur.

But, maybe the best defense of all wasn’t men or weapons, but the mountain itself. A sheer rock face almost all the way around with mostly steep drop offs. Anyone climbing would endure a tiresome journey up thousands of feet hauling weapons to storm the peak. No way could it be accomplished without incurring heavy losses. And as for climbing up the cliff nearest the site, this would entail the most perilous undertaking of all, as it was steepest in this area.

Impossible.

Yes it was. And yet, it was done.

North Vietnam had eyed events at Lima Site 85 from its beginning, with increasing curiosity. It knew of the many CIA outposts in inaccessible areas supplied only by helicopter, but this went beyond a few thatched huts with tribesmen as guards. So as intelligence developed it into something more significant, the aforementioned air attack flown by North Vietnamese pilots occurred. When that failed it was decided something bolder, though riskier must be tried.

A platoon of 33 men led by First Lieutenant Truong Muc which had just completed 9 months of extensive training including scaling cliffs and fighting in mountains was chosen for the task. Known as ‘sappers’, they would scale Phou Pha Thi, kill its occupants, gather what intel they could, then blow the facility.

To accomplish this they outfitted with 23 AK47s, 4 SKSs with 200 rounds of ammo for each man, 3 RPG-7’s with 6 rockets each, 6 hand grenades, 14 ounces of explosives and 15 days of rations. All told each man would carry up to 99 pounds of supplies.

Muc’s men would operate within a much larger force of 3,000 NVA and Pathet Lao (Communist ally) troops backed by mortar, artillery and rocket fire. The plan was for the main force to target the 1,000 or so Hmong fighters (800 on lower parts of the mountain, 200 in the valley) bombard, then engage them.

During the battle the 33 men would slip through and climb the most inaccessible, treacherous part of the mountain, a path chosen because it was least the likely to be watched. Once on top, they would cut through the concertina wire and probe the mined walkways, then hit the site with lightning speed.

In early March, the 33 boarded trucks that joined with countless others in a never ending stream down the Ho Chi Minh Trail. After they linked up with the main force they made their through the undulating hills and jungle towards the target. On March 10, with the calm determination months of training had imparted in them, they peered through the foliage at the massive scale of the mountain and waited for the attack to begin.

At about 6 P.M., that evening, rockets and shells arced down upon the mountain from north and east, Impacts flickered all over Phou Pha Thi, as the communists rushed forward and broke through the valley security. Way above, those at the site could do little but wait out the attack and keep Ambassador Sullivan informed.

After the barrage ceased at about 7:45 P.M. Lima Site 85 inspected itself again. Little damage had been done and even though the Hmong fighters on the mountain were now engaging troops in the valley, the facility was still operating. They received word from Sullivan that air assets were available to strike the valley and evacuation choppers on standby.

Bombardment resumed at 9:20 P.M., and 30 minutes later the 33 sappers began planting boots against a rock wall so high that it seemed to stretch to the clouds. While they made their way upwards, small arms fire intensified near the Hmong positions on the mountain as NVA attempted a frontal attack up the slopes, as the last rays of the sun faded to black.

With the barrage halting again and battle going on below, the men of Lima Site 85, settled into an uneasy rest worrying if the Hmong could hold off the NVA or if they would be evacuated soon. They had no idea as the night grew longer that just a couple hundred meters away, the Sappers had completed their climb cleared the obstacles and were approaching from behind, their steps silent as the made their way over the scree of sharp rocks and vines.

Just after 3:00 A.M. they bumped into a Hmong guard. Gunfire rang out. And Muc’s men charged the position in 4 man cells firing from the hip and hurling grenades.

An RPG rocket wooshed into the TACAN equipment, destroying it in a plume of sparks and smoke. Shocked personnel fell out of buildings being hit by RPG’s to be cut down by AK fire or grenade blasts.

Still, some managed to shrug off the surprise and fought back.

M16 fire interrupted the heavier reports of the AK’s as the airmen tried to draw down on the fleeting shadows. The fighting raged for one hour then two as burning buildings lit up the mountainside with pulsing flames between which the Sappers searched for the hiding Americans.

Sullivan received reports of the unfolding carnage from a CIA source in the valley, and ordered the site evacuated.

At first light, CIA choppers arrived over the wreckage of the compound. With reports of survivors in the ruins they hovered nearby as A-1 Skyraiders rolled in to strafe the site, and the remaining airmen, 6 in all, made for the door.

One of these, Chief Master Sergeant Richard Etchberger refused evacuation, defended his team, and helped load 4 of his wounded comrades into a sling. Just as the last was off the ground, he was hit from rounds coming up through the floor and fell dead as the chopper pulled away. Behind them, the Skyraiders continued exchanging fire with Muc’s men hiding amid the smoldering ruins.

Lima Site 85 was no more.

Fighting down the rest of the mountain ended soon thereafter, with the Hmong driven off and it forever falling into communist hands.

“The Americans were taken by surprise.” A North Vietnamese report on the battle later concluded. Perhaps, there was no need for any more comment.

In 2010, after a further review of Etchberger’s actions, his award of the Air Force Cross was upgraded to the Congressional Medal Of Honor. President Barack Obama presented his 3 children with the award in a ceremony September 21st.

And to think, the very day he died, he and several others at the site were just hours away from going home.

Material on Lima Site 85 was declassified in 1983. 13 U.S. personnel were reported Killed In Action/ Body Not Recovered (the largest ground loss of USAF personnel in the war), along with 42 Hmong killed.

1 NVA Sapper was killed and 2 wounded.

Recent excavations at the site revealed the American bodies were thrown off the cliff once the battle was over.

Only one has ever been found and returned to the U.S.