During the Vietnam War, the North Vietnamese were trying to find ways to force the United States out, as they had the French. In December 1967 they figured the Marine base at Khe Sanh would be the perfect place to replicate Dien Bien Phu, their decisive victory against the French in 1954.
Well, the French didn't have the air power of the United States Air Force and United States Marine Corps. Nor did they have cargo planes like the C-130 Hercules and the C-123 Provider.
First-generation C-130As performing an airdrop (Photo US Air Force)
This was one of two big game-changers in the years since Dien Bien Phu. The cargo planes France had back then were C-119 Flying Boxcars – which could haul almost 14 tons of cargo. The French had as few as nine planes in that theater.
The American C-123s could carry 12 tons, but the C-130s could carry over 22 tons – and the Americans had a lot more airlift assets. This meant a lot of supplies got to the Marines – 12,430 from just the Air Force, and another 4,661 tons via Marine helicopters.
One other big difference: The B-52 Stratofortress. Yes, BUFFs were at Khe Sanh, compared to second-hand A-26 Invaders. A B-52 could drop 51 M117 750-pound bombs on a target. The A-26 could carry 6,000 pounds of bombs – or up to 12 500-pound bombs.
That did not include the support from other planes like the F-4 Phantom and A-4 Skyhawk.
Over 20,000 sorties were flown in defense of Khe Sanh – 2,500 of which were flown by B-52s. When all was said and done, the North Vietnamese lost 15,000 personnel trying to take Khe Sanh – making the siege a costly error. The base was eventually relieved, and a lot of abandoned gear was captured.
The video below from the DOD provides an excellent outline of just how American air power caused the siege of Khe Sanh to fail.