Operation Niagara: Siege of Khe Sanh

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The most spectacular display of air power at Khe Sanh was provided by the B-52 Stratofortresses. The B-52s had a payload of 108 500-pound bombs per plane, and these strikes, code-named Arc Lights, were conducted against targets such as troop concentrations, supply areas and bunker complexes. These targets were programmed into on-board computers and were launched from altitudes above 30,000 feet. Arc Light bombing procedures were based on a grid system, in which each block in the Niagara area was represented by a box superimposed on a map. Three B-52s, composing one cell, could effectively blanket a box with high explosives. On average, every 90 minutes one three-plane cell of B-52s would arrive on location around Khe Sanh and be directed to a particular target by a controller. Several cells of B-52s could churn up boxes of terrain several thousand meters long. Many enemy casualties were due to concussion alone. In some instances, NVA soldiers were found after an Arc Light strike wandering around in a daze, blood streaming from their noses and mouths. To catch these stunned survivors, artillerymen at Khe Sanh often brought massed artillery fire down onto the Arc Light target area 10 to 15 minutes after the heavy bombers departed.

Arc Light attacks delivered a total of 59,542 tons of munitions from 2,548 sorties during the siege. General Westmoreland was elated at the performance of B-52s. According to Westmoreland, the thing that broke the back of the NVA at Khe Sanh was ‘basically the fire of the B-52s.’

Arc Light attacks had some limitations, however. An NVA soldier captured in April 1968 told his interrogators that his unit received frequent, timely and accurate warnings of impending B-52 attacks. The alerts came either by radio or telephone and usually provided two hours’ notice. The NVA prisoner was not certain as to the origin of these warnings. Possibilities include Soviet intelligence-gathering trawlers operating in the Pacific, and the interception of communications sent to or from the MACV combat operations center at Tan Son Nhut air base near Saigon.

The target intelligence officer at Khe Sanh, Captain Mizra M. Baig, felt that Arc Light was an accurate weapon that could be employed around Khe Sanh much the same as other supporting arms. However, since requests for B-52 strikes had to be submitted 15 hours prior to the drop, Arc Light raids could never be as responsive or flexible as tactical air and artillery. The FSCC developed ways to combine the strengths of aerial and artillery support. One technique was the Mini-Arc Light.

When data indicated that NVA units were in a certain region, the FSCC computed a 500-by-1,000-meter box in the center of the suspected assembly area or likely route of movement. Two A-6 Intruders, each armed with 28 500-pound bombs, were placed on station. Army 175mm guns at the nearby artillery bases at Camp Carroll and the Rockpile initiated the Mini-Arc Light by pouring 60 150-pound rounds into one half of the block. Thirty seconds later, the A-6s unloaded their ordnance in the middle of the block. At the same time, the artillery at Khe Sanh poured an additional 200 artillery and mortar rounds into the target area. Fire coordination was such that bombs and artillery shells hit at the same instant.

The Mini-Arc Light could be put into effect in about 45 minutes. To reduce reaction time even further, a Micro-Arc Light was executed. The block size was reduced to a 500-by-500-meter area. Any aircraft on station could be used for bombing. Twelve to 16 500-pound bombs, 30 175mm artillery rounds, and 100 mixed lighter artillery rounds from Khe Sanh batteries could be unloaded on the target block within 10 minutes. On an average night, three to four Minis and six to eight Micros were executed in the vicinity of the Khe Sanh combat base.

Because the Marines at Khe Sanh were surrounded by NVA, the base could be neither supplied nor evacuated by ground operations. An effective method of aerial resupply was vital, and the base’s principal source for supplies was Da Nang, a 30-minute flight away. Lockheed C-130s and Fairchild C-123s delivered the bulk of the supplies. Transport crews used speed-offloading techniques to minimize time spent on the ground at Khe Sanh. When weather or hostile fire prevented transport aircraft from actually landing at the airstrip, parachute and various cargo-extraction systems were used to unload cargo without putting the planes’ wheels on the ground.

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Tags: 20th - 21st Century, Airborne Operations, Vietnam War

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