Triggering the mine called for the best fuses the engineers could create. The primary fuse was a radar-activated detonator used in the 1950s’ Bomarc surface-to-air missile. A high-altitude bomber killer, Bomarc, officially the CIM-10, was designed to detonate when its onboard radar detected a target aircraft overhead. At Eglin the backroom boys made the fuses smarter by tweaking them to distinguish between a bridge’s large structure and lesser items that might appear above the mine, such as birds or a telephone wire. As a backup in case the radar fuse failed, the mines received an infrared sensor that would detonate when it sensed the ambient heat emitted by a large metal structure.
In all, thirty Carolina Moon mines were produced, including ten without warheads for training missions. The mines were expensive: $20,000 each, for a total cost of $600,000 in 1965 dollars, which would be the equivalent of $4.8 million in 2018.
Although Eglin was the Air Force’s weapon-testing center, the base had no suitable facility to evaluate the entire mission profile. Consequently Fairchild C-123 Provider and Lockheed C-130 Hercules transports dropped training “shapes” offshore. Retarded by parachutes and dropped from an altitude of four to five hundred feet, the mines splashed into the ocean when the chutes that dragged them out of their airplanes automatically released. At that point engineers observed whether the weapons would float… and they did.
Subsequently some mines were detonated beneath test structures to determine what the effects would be on the Dragon’s Jaw and other spans. The results were promising, with the blast energy focused along two axes, vertically and horizontally, to achieve maximum effect.
America had a new infernal device.
Now all the Air Force needed to do was put a mine in the Ma River. A specially modified B-52 would be just the ticket, but a B-52 five hundred feet over the Ma River? The airplane selected was the C-130 Hercules.
In the 1950s Lockheed was doing a booming business manufacturing fighters and reconnaissance planes when the Air Force requested proposals for a multiengined transport. Some Lockheed executives, including Kelly Johnson, designer of the P-38 Lightning and F-104 Starfighter and future landmarks, including the U-2 and SR-71 spy planes, doubted there would be much of a market for a combat transport. Despite their reservations, Johnson and Vice President Hall Hibbard inked the contract in 1951.
The C-130 was one of the first aircraft designed to use turbo-prop engines, four of them. Each Allison T56 provided more than four thousand horsepower, enabling the Hercules, the “Herc,” to lift its own weight. With reversible propellers, a C-130 could get into short airfields, and its impressive power-to-weight ratio permitted short takeoffs as well. The rear ramp permitted rapid loading and unloading, a quantum advance over side-loading aircraft.
First flown in 1954, the Hercules entered service two years later. Tremendously versatile, in addition to hauling cargo it has served as an aerial tanker, medevac, airborne command post, special operations platform, and paratroop lifter, plus numerous other roles, including aerial firefighter. As the AC-130 Spectre, it served as a gunship in Vietnam. The Hercules was widely exported to some seventy nations, from Afghanistan to Zambia. At this writing in 2018 updated models of the C-130 are still in service in the US Marine Corps, Air Force, Air Force Reserve, and National Guard as well as forty militaries around the world. On the world stage the Hercules starred in Israel’s spectacular rescue mission to Uganda in 1976, flying unrefueled twenty-five hundred statute miles to Entebbe, where commandos freed Jewish hostages.
Perhaps the greatest tribute to this amazing aircraft is that the C-130J Super Hercules is still in production—sixty-four years after the first Herc took to the skies.
The Carolina Moon project managers began with several possible C-130 crews before selecting two from Sewart Air Force Base in Smyrna, Tennessee. Both crews were led by experienced airlift pilots: Majors Richard T. Remers and Thomas F. Case. Beginning in January 1966 the crews worked under extreme secrecy at Eglin, often wearing civilian clothes off base. In all, the Carolina Moon project involved sixty-nine military and civilian personnel.5
The airmen learned that Carolina Moon required more than simply pushing the load out the back of the airplane—delivering mines accurately was a complex operation, calling for a reliable means of opening the parachutes to extract the weapons from the back of a Herc and accurately placing the two-ton weapons in the middle of the river. Because water depth, currents, and wind affected delivery to the desired point beneath the bridge, extremely detailed intelligence was required.
Ordnance and operations officers huddled frequently to refine Carolina Moon tactics. A night mission was obviously required, as flying a transport over North Vietnam in daytime would be suicidal. The ingress and attack profile would need to be flown low, at five hundred feet, to minimize the possibility of discovery by enemy radar. Mission planners chose an inbound leg of forty-seven nautical miles, which would take 18.8 minutes to cover, assuming no navigation errors, as the Herc flew at a speed of 150 knots. Eglin’s sprawling real estate afforded training sites resembling the terrain expected near Thanh Hoa. During practice missions Remers’ and Case’s crews became familiar with what they would likely see during the actual attack.
Each attacking aircraft would drop five mines between one and two miles upstream of the Dragon’s Jaw. It was uncertain whether one mine would actually drop the bridge, so multiple weapons allowed a margin for error. In war always go for overkill.
The project team, now down to forty-one men, including four civilians, left for Vietnam in mid-May 1966. At DaNang the maintainers and “ordies” assembled ten mines by May 22. Two crews, two planes, and two loads of weapons seemed optimal in case the first mission failed for any reason.
Carolina Moon was vetted and approved at the highest theater levels, Admiral Sharp’s Pacific Command and Lieutenant General Joseph H. Moore’s newly established Seventh Air Force. Joe Moore was a pragmatist. As a pursuit squadron commander in the Philippines in 1941, he said the one benefit of war was that “at least we could throw away our damn ties.” He was willing to consider innovative solutions to thorny problems. Besides, he had an additional reason: his son, also Joseph, was a Phantom pilot.6
Seventh Air Force maintained a steady flow of information to the Hercules’ crews. Reconnaissance and intelligence updates showing changes in North Vietnamese gun positions were inserted in the mission plan. The routes in and out were altered accordingly.
But the fliers had ultimate responsibility for their work. Both command pilots believed the Herc’s rugged airframe could absorb moderate flak damage, and four Allison turboprops gave them an excellent chance of remaining airborne with one or two engines inoperative.
The aircraft commanders arrived at differing solutions regarding a low-altitude emergency. Because the fliers could not wear body armor and parachutes simultaneously, Remers decided that his men would wear chutes, expecting to be able to climb to a reasonable bail-out altitude if necessary. The airmen would lay their armored vests on the floor as extra protection. Case took the opposite tack: his crew would wear flak vests and store the parachutes.
Shortly after arrival at DaNang the Carolina Moon crews received notice that the first mission was scheduled for May 30. But May 27 brought chilling news. Seventh Air Force reported five new heavy-caliber antiaircraft sites and a huge increase in automatic weapons in the target area. Nonetheless, operations officers and the two command pilots believed the risk was acceptable: Carolina Moon was a go.7
To improve the Herc’s odds, an attack to divert the North Viets’ attention during the mining was laid on. Four Phantoms of the Eighth Fighter Wing at Ubon, Thailand, would attack Route 1A, the coastal highway fifteen miles south of Thanh Hoa. Bombs and flares released shortly before the Herc’s target time would certainly attract Vietnamese notice. Additionally, two Douglas EB-66 Destroyers of the 41st Tactical Reconnaissance Squadron from Takhli, Thailand, would jam known Vietnamese radar frequencies for the critical period of the a
ttack.8
With planning complete, Carolina Moon needed only one or two nights of good weather with a decent moon. Without a radar to navigate and provide terrain avoidance, Remers and Case needed to be able to see the ground to avoid it, and the navigators needed to see their turn-points. And they would need to see the river and the bridge.
At 12:25 A.M. on May 30 Remers and copilot Thomas M. Turner advanced their four throttles and accelerated down DaNang’s active runway. The flight engineer, Master Sergeant John R. Shields, monitored the performance of sixteen thousand screaming horsepower. Banking seaward beneath an eight-tenths moon, they stayed at about a hundred feet over the ocean, then turned northbound while maintaining radio silence.
Thanh Hoa lay 220 nautical miles ahead. Seven Americans were off to slay the sleeping dragon.
Both crews had two navigators to increase chances of spotting the primary or secondary drop points. Remers’ navigators, Captain Norman G. Clanton and First Lieutenant William R. “Rocky” Edmonson, meticulously noted the time on their charts as they crossed the coast-in point, providing a datum for the leg to the initial point. Remers advanced his throttles, climbing to four hundred feet, then retarded the throttles to slow to the optimum 150 knots.
North Vietnam was quiet. Gauzy moonlight diffused by the ever-present haze reflected from rice paddies as the minutes ticked away at an agonizing pace. Making just two-and-a-half nautical miles a minute, the Herc finally reached the initial point and turned for the first drop point. So far, so good—the Phantom diversion seemed to have achieved its purpose.
There was the river! With the ramp down and the loadmasters ready, the pilots flew down the river toward the bridge. The tension wound tighter and tighter as the seconds ticked away. With no flak at the first drop point, Remers pressed ahead to the second drop point, a mile nearer the bridge.
Suddenly Vietnam lit up with muzzle flashes and tracers.
The gun crews of the 228th Air Defense Regiment heard the throaty drone of four turboprops in the darkness; the command post sent all units to Alert Condition One.
The Herc crew worried that the gunners would see the big, slow transport in the moonlight, distinctive with its high, pointed tail. Heavy and light AAA fire flashed and flared around the transport, but was poorly directed. The crew reckoned that the nearest gunfire fell hundreds of feet astern: the gunners couldn’t see the Herc and were shooting at sound, which meant they shot at where the airplane had been, not at where it was.
On the signal from the pilots Staff Sergeant Aubrey B. Turner and Airman Johnny A. Benoit initiated the sequence of popping chutes to drag the five mines out of the open rear of the aircraft, one by one. Once released from the shackles that secured them, the mines went out easily on rollers. Flying the plane slightly nose-up helped. The parachutes blossomed ghost-like in the Indochina darkness starting about a mile and a quarter upstream of the Dragon’s Jaw.
Air Force lore insists that during the bomb run you’re on the government clock; on egress you’re on your own. With the last mine gone, Richard Remers coordinated ailerons and rudder, turning hard right while descending back to relative safety at a hundred feet above the planet.
When they crossed the pale white ribbon of the beach and achieved the sanctuary of the Tonkin Gulf, the crew was euphoric. From their perspective the mission was a rousing success. Back at DaNang the men posed for an early-morning photo shoot and celebrated with adult beverages. They had done it and lived to tell the tale!
Like a Broadway premiere’s cast awaiting the reviews before breakfast, Remers’ men and their friends stood by for the morning recon reports.
The two early-morning RF-101 pilots returned to DaNang, where the film cassettes were removed from their Voodoos’ noses. After immediate processing, the photo interpreters scrutinized the barely dry prints, seeking some sign of damage to the bridge.
Nothing.
In addition, none of the five mines were visible along the bank, upstream or downstream. They had simply disappeared.
According to a North Vietnamese account published years later, “Troops had seen parachutes descending over the upstream ferry crossing, and Colonel Nguyen Van Khuy dispatched soldiers to investigate. They reported mines floating toward the bridge, prompting the commander to order an impromptu response. Four soldiers sprinted to the riverbank, expending all their rifle ammunition on the visible mines. Some of the weapons exploded under accurate gunfire. In the morning engineers from the province military headquarters and some public security personnel retrieved stranded mines and detonated them.”9
You may believe this nonsense if you wish, but rifle fire probably could not detonate the mines. The fusing was sophisticated—proximity and infrared—and the Viets had no idea of where to aim even if they were accurate. Furthermore, removing two-ton mines from a river was not a job for troops in a sampan—heavy equipment would be required.
Regardless of the truth of the North Vietnamese account, the fact was that the mines apparently failed to detonate under the bridge. Perhaps failing to detonate, the mines were carried by the river on out to sea. If they did explode, they didn’t take the structure down.
It is possible that the mines missed the river altogether and fell on land. Another possibility is that the mines plunged too deep into the water when released by their parachutes and buried themselves in the mud at the bottom. However, the most likely scenario is that the swirling eddies of the river washed the mines into shallows, where they were stranded. The unpredictable currents of the river were always the weak link in the plan. If so, the North Vietnamese probably pulled the mines above the high water line.
We are left with the mental image of a North Viet explosive ordnance disposal (EOD) squad detonating one of the captured mines without any idea of its tremendous explosive power. If they did, one suspects they might have been instantly launched into the hereafter, maybe all the way to Communist heaven, if there is such a place, to hang out with Karl Marx, Lenin, and Stalin while awaiting Uncle Ho’s arrival.
Meanwhile, back at DaNang, the powers that be ordered the second Carolina Moon mission launched that night.
The aircrews were incredulous. Even with another diversion and radar jamming support, repeating the mission so soon invited disaster. The North Vietnamese would be on alert and waiting. The aircraft commanders clashed vocally with their superiors, to no effect.
The order stood.
One of Major Case’s loadmasters was Airman First Class Elroy E. Harworth, a twenty-four-year-old Minnesotan with nearly six years’ service. He had a baby boy and a pregnant wife and confided to his wife in a letter that he and the other crewmen felt that they were going to die in Vietnam.10
In the daylight hours remaining, Carolina Moon planners revised the mission profile. Time over target was pushed back half an hour, and ingress-egress routes were altered to avoid repeating the first mission’s route. The main difference was Major Tom Case’s decision to take one of Remers’ navigators. First Lieutenant Rocky Edmondson’s experience from the previous night offered an advantage that Case wanted to tap.
The second Hercules, Radium One, tucked its wheels into the wells at 1:10 A.M. on May 31. Due to strict radio silence, no Americans followed the progress of the mission.
The Hercules was expected to return to DaNang around 3:45 A.M., but as dawn broke, hope ebbed. Case’s aircraft had disappeared without a word. The diversionary fighter crews reported flak near the bridge followed by a large explosion on the ground about two minutes before the scheduled attack time.
Perhaps twenty aircraft, including Remers’, searched for the missing Herc through most of the day but found nothing. Major Tom Case, a thirty-four-year-old Georgian, had vanished with his seven-man crew—copilot First Lieutenant Harold J. Zook, EWO Captain Emmett R. McDonald, navigators Rocky Edmonson and First Lieutenant Armon D. Shingledecker, flight engineer Staff Sergeant Bobby J. Alberton, and loadmasters Airmen First Class Harworth and Philip J. Stickney.11
Aga
in, aerial reconnaissance showed no damage to the bridge. Later search-and-rescue aircraft spotted an empty life raft and some wreckage, probably not from Radium One.
Subsequent aerial photography revealed a cable strung across the Song Ma about fifteen hundred yards upstream. Analysts theorized that the barrier might have blocked some of the mines laid in the river.
Postwar searchers found that the C-130 crashed in virgin jungle well west of Thanh Hoa. According to the North Vietnamese, it had been solidly hit by 228th Regiment gunners near Tho Xuan’s (also called Bai Thuong) “Yellow Star” airfield about twenty-five miles upstream and exploded in midair. This account is doubtful. A more likely scenario is that after the Herc was severely damaged by flak over the river, Tom Case turned toward Laos and climbed so the crew could bail out there if necessary. It may or may not have been hit again by flak. In any event, Radium One didn’t make it out of North Vietnam. The remains of three crewmen were returned in 1986 and two others in 1998.12
At an unspecified date long after the attack, US intelligence officers interrogated a North Vietnamese sailor from a sunken PT boat. He said that four mines from the second attack hit the bridge but caused no lasting damage.13
Some official and quasi-official sources state that one of two diversionary Phantoms was lost while supporting the second Carolina Moon mission. The missing F-4C crew from the Eighth Tactical Fighter Wing included Major Dayton Ragland, a Korean War POW who had packed his bags, expecting to rotate home the following day. He was providing a combat checkout for the front-seater, First Lieutenant Ned Herrold, new in theater.
However, neither the timing nor the location of the Phantom loss seems to fit the C-130 mission profile. An official source lists the Phantom down nearly three hours before the Herc, some thirty miles south of the target area. Moreover, an unofficial source says the F-4 took off six hours before the bridge attack.14
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