Calculated Courage at Thai Nguyen

Feb. 1, 2006

The target on March 10, 1967, was the iron- and steelworks at Thai Nguyen in the Red River delta, 35 miles north of Hanoi. The Joint Chiefs of Staff listed it as their top industrial target in North Vietnam, but, because of constraints imposed by Washington on conduct of the Vietnam War, it had been off limits to air strikes until now.

The plant was located near the small town of Thai Nguyen. It was part of a sprawling industrial complex that occupied about two square miles. Earlier in the year, US aircraft had bombed the railroad marshaling yard and supply depot at Thai Nguyen, but the main industrial complex was left untouched.

The ironworks, built by China in the 1950s, was the pride of North Vietnamese industry. The country had two other foundries, both of them smaller. For some time, Thai Nguyen had been making products with imported steel. More recently, a steel mill—the only one in North Vietnam—had been built at Thai Nguyen.

In January 1967, Adm. U.S. Grant Sharp, commander in chief of US Pacific Command, requested permission for a series of air strikes “to systematically flatten North Vietnam’s military and industrial base” with “the Thai Nguyen iron-and-steel plant at the head of the list.”

President Johnson on Feb. 22 approved Thai Nguyen as a target, but Southeast Asia was in the middle of the wet season monsoon and the first strike was scrubbed eight times because of bad weather. The mission was on hold again the morning of March 10, but a break in the weather was forecast for later in the day. The strike force launched just before noon to be over the target at 3:30 p.m.

The strike force included 72 aircraft from three bases in Thailand. There were F-105s from the 388th Tactical Fighter Wing at Korat, which went in first, followed by F-105s from the 355th TFW, Takhli, and F-4 Phantoms from the 8th TFW at Ubon. In addition to carrying bombs, the F-4s were responsible for protecting the strike force from MiG interceptors.

The F-105—officially Thunderchief but known to all as the “Thud”—flew most of the bombing missions against North Vietnam. It was fast at low level but was at a disadvantage in a turning fight with MiGs. The F-4, newer and more agile, could handle any of the North Vietnamese fighters, including the MiG-21.

The strike force aircraft refueled in the air from tankers over Laos and entered North Vietnam. They crossed the Red River and flew down the back side of Thud Ridge, continuing on to Cho Moi before looping back toward Thai Nguyen.


The air defenses were thick in the North Vietnamese heartland, and the gunners were ready and waiting. One of the pilots that day said the flak was the heaviest he had ever seen “except in World War II movies.”

Thai Nguyen was ringed by 96 anti-aircraft artillery (AAA) sites, each with several guns. North Vietnam’s main fighter base, Phuc Yen, lay nearby, between Thai Nguyen and Hanoi. US pilots were forbidden to attack the base, and the North Vietnamese knew it. The industrial complex also was protected by SA-2 surface-to-air missiles (SAMs).

The AAA was particularly effective at close range. US fighters could reduce their vulnerability by going to higher altitude, but that was where the SAMs were most lethal.

The Wild Weasels, flying specially equipped F-105Fs, had been created expressly to suppress the SAMs.

The March 10 strike force included two flights of Weasels, one from Korat and one from Takhli. The Weasels’ tactic was to use themselves as bait. They “trolled” for SAMs, tempting them to turn on their Fan Song tracking radar or fire a missile. If they did, the Weasels would home on the signal and launch a Shrike antiradiation missile to follow the beam back to its source and destroy the radar. The site could then be finished off with guns or bombs.

The Takhli Weasels that day, call sign Lincoln, were several minutes in front of the rest of the 355th aircraft, allowing themselves time to work the SAMs before the strike flights got there.

Lincoln flight consisted of two elements of two airplanes each. The element leaders flew F-105Fs, two-seat models configured with electronics and other equipment to detect and destroy the SAM radars. They were armed with Shrike missiles, CBU-24 cluster bombs, and 20 mm Gatling guns. The Lincoln wingmen flew standard Thuds, F-105Ds, which had guns and a full load of bombs. On “Iron Hand” missions, the F-105Fs found and knocked out the SAM radars and the F-105Ds came in to demolish the site.

The flight commander was Maj. David A. Everson, Lincoln 01, with Capt. Donald A. Luna, the electronic warfare officer (EWO), in the back seat. Capt. Bill Hoeft was Lincoln 02. The leader of the second element was Capt. Merlyn Dethlefsen, Lincoln 03, with Capt. Kevin A. “Mike” Gilroy as his EWO. Flying on his wing was Maj. Kenneth H. Bell, Lincoln 04.

All six airmen in the Weasel flight had plenty of experience. Each of them had flown more than 50 combat missions and had been to North Vietnam many times.

“We were the eyes and ears of that strike force,” Dethlefsen told Airman magazine in 1969. “That target was very important. It produced about 40 percent of the enemy’s steel. The SAM sites were there to protect it from our air strikes. The strike force would be very vulnerable to the SAMs and anti-aircraft guns. Keeping them down was our job.”

First Element Lost

If the defenders at Thai Nguyen needed any stirring up, the Korat F-105s in the first wave of the attack had done a proper job of it.

“After we turned south, there was absolutely no doubt about the target location,” Bell said in his 1993 book, 100 Missions North, published by Brassey’s. “Thai Nguyen was ablaze with AAA fire and a large column of black smoke covered the area,” Bell said. “The 388th was in the thick of it, and we were a minute away from the most intense barrage of ground fire I had ever seen. Several SAM sites were up and tracking us, but their threat paled in comparison to the guns. The defenses were ready and Thai Nguyen was a boiling mushroom of ugly black flak.”

After the mission was over, Gilroy remembered how some of the flak rounds, reaching the end of their range and losing velocity, rattled like pea gravel off the bottom of the aircraft’s wings.

Lincoln flight approached Thai Nguyen in combat spread formation, the four aircraft almost line abreast with Everson and Hoeft on the right and Dethlefsen and Bell on the left. Two miles out from the target, the Weasels detected a SAM radar tracking them.

Everson in Lincoln 01 attacked first. He swept wide to the right, dived through the flak, and launched a Shrike missile toward the SAM site. Seconds later, Lincoln 01 took a critical hit from the AAA. Chute beepers confirmed that Everson and Luna had bailed out. They reached the ground and were captured immediately. They spent the rest of the war as POWs, returning in the general repatriation in 1973.

Hoeft, Lincoln 02, followed Everson into the flak. He was also hit and put out of action. An 85 mm shell blew a four-foot hole in his left wing, just outboard of the landing gear. He was lucky to make it to Udorn Air Base in northern Thailand, where he recovered.

Dethlefsen Takes Over

That left Dethlefsen, Lincoln 03, in command of the two remaining Weasels. Merlyn Hans Dethlefsen, 32, was a former Iowa farm boy. He joined the Air Force as an enlisted man and earned his commission and navigator’s wings through the aviation cadet program in 1955. He later went to pilot training, graduating in 1960. He flew F-100s at first, then moved into F-105s. He had come to Takhli in October 1966. This was his 78th combat mission.

The prevailing wisdom among fighter pilots was not to linger in situations where the air defenses were intensive. Making more than one pass was regarded as a high risk. Merlyn Dethlefsen would make five passes at Thai Nguyen. He also would stay in the target area for 10 minutes, which must have seemed an eternity.

“We were still ahead of the strike force and they were still vulnerable,” Dethlefsen said. “We had fuel and missiles and guns and bombs, and the job wasn’t done yet. Lincoln lead had seen the target and launched a missile, but it had missed. I decided we would stay. Coming around, I studied the flak pattern. It wasn’t a matter of being able to avoid the flak but of finding the least intense areas.”

On the first pass, Gilroy, operating the electronics in the back seat of Lincoln 03, got an approximate fix on the SAM site. The two Thuds emerged from the flak with numerous bullet holes. Dethlefsen, in the words of a subsequent nomination for the Medal of Honor, “was now the subject of three defensive systems—the MiGs, SAMs, and anti-aircraft artillery.”

As Dethlefsen came around for the second pass, the F-105 strike flights arrived and began dropping bombs on the steel mill.

The signal from the SAM radar was strong. As Dethlefsen lined up to attack it, two MiG-21s pulled into shooting position behind Lincoln 03 and 04. Dethlefsen kept his concentration on the target. Just as one of the MiGs fired a missile, Dethlefsen launched a Shrike against the SAM site.

“I broke to the right, down through the flak,” Dethlefsen said. “I figured that would give me the best chance of evading both the heat-seeking missiles and the MiG’s guns. Didn’t think the MiGs would want to follow me through that stuff. They didn’t.”

The two Weasels had eluded the MiGs by going low, but that took them into the teeth of the AAA. Dethlefsen had taken several hits from the 57 mm guns and perhaps from the MiG cannon, but his engine and flight controls were still in good order.

Bell, in Lincoln 04, had sustained battle damage that was much more serious. “My right wing had been damaged,” he said. “The right leading-edge flap was blown down, forcing the airplane into a left turn because of added lift from the right wing. I was able to hold the wings level with cross controls, but it added a difficult complication. … I had to settle for cross controls and hope for turns to the left.”

The Weasels could have left Thai Nguyen when the strike force did, but that wasn’t the way Dethlefsen interpreted his duty.

“I could hear the strike force withdrawing,” Dethlefsen said. “I had permission to stay there after they left. That steel mill with the related industry was a big target—too big to knock out with one strike. I knew those fighter-bombers would be back tomorrow. Same route, right over this area. My aircraft was working well enough to be effective. With the weather the way it was that day, I knew we would never have a better chance. So I made up my mind to stay until I got that SAM site or they got me.”

As the Weasels turned back in to the defenses of Thai Nguyen, Dethlefsen saw a different SAM site dead ahead. He fired his second Shrike and the radar abruptly went off the air. Bell, holding close on Dethlefsen’s wing with some difficulty because of the damaged flap, did not have a good angle but dropped his bombs on the site anyway.

On the next pass, Lincoln 03 and 04 came in low, looking for the original SAM site. Dethlefsen saw the radar van and pickled his CBU-24 fragmentation bombs onto it as they roared past. Turning, Dethlefsen and Bell came back across and strafed the site with their guns.

The Medal of Honor nomination continued, “As he completed the attack, a large part of the SAM site was engulfed in secondary fires. Only then did Captain Dethlefsen depart the area. Low on fuel and unable to reach his assigned base, he was forced to an emergency forward operating base where he successfully landed his battle-damaged aircraft.”

Medal of Honor

Lt. Col. Phil Gast, who led the Takhli strike force that day, knew that the Weasel engagement at Thai Nguyen had been something special. He asked Maj. Hal Bingaman to look into the details of what happened.

Dethlefsen did not fit the stereotype of the flamboyant fighter pilot, Bingaman said. Dethlefsen and Gilroy explained to Bingaman that it had been a tough mission, but they did not embellish it. They were reluctant to depict their achievements as having been that dramatic or extraordinary.

“I had to drag it out of them,” Bing­aman said. He was struck by how well the pilot and EWO had worked together. “Without Mike Gilroy’s instant inputs there’d not have been the timing there for even the first pass, much less the other four,” Bingaman said.

The wing thought Dethlefsen’s actions were worthy of the Medal of Honor and nominated him for it. Gilroy and Bell were put in for awards as well.

Meanwhile, operations against Thai Nguyen continued. It was the Air Force’s leading target in North Vietnam for the next month and a half. By the end of April, air strikes had put the iron- and steelworks out of business.

Six aircraft were lost, all in the first two days. Lincoln 01 was lost on Day 1, as were two F-4s from Ubon. Three more F-105s from Takhli were shot down the next day. One of the F-105s was brought down by a SAM. AAA accounted for the other five.

Merlyn Dethlefsen finished his combat tour, 100 missions over North Vietnam, in May and returned to the States as a flight instructor at Vance AFB, Okla. Dethlefsen was there when he learned that he was to receive the Medal of Honor.

The presentation was made by President Lyndon B. Johnson at the White House on Feb. 1, 1968. Johnson noted that Dethlefsen’s actions had not been a momentary impulse.

“He had plenty of time to think about the danger to himself, to figure the odds, even to turn away,” Johnson said, “but his courage was calculated. It came not from desperation, but dedication. He answered a call far beyond duty.”

Gilroy was awarded the Air Force Cross and Bell the Silver Star.

After his tour at Vance, Dethlefsen went to the Air War College at Maxwell AFB, Ala., and from there was assigned to the faculty at Army War College at Carlisle Barracks in Pennsylvania. In 1974, he went to Beale AFB, Calif., as assistant director of operations for the SR-71 wing. In 1975, he was assigned to Dyess AFB, Tex., as director of operations for the B-52 wing. He retired from there as a colonel in 1977.

He then relocated to Fort Worth, Tex., where he headed his own small business, Home Medical Equipment Co., until 1986. He died in 1987 and is buried at Arlington National Cemetery.

Doing His Job

When Merlyn Dethlefsen spoke of the events at Thai Nguyen, it was with understatement and a strong sense of duty.

“He was very modest and unassuming,” said his son, Jeff Dethlefsen. “He always just felt that he had a job to do and did it the best he could. I don’t think he ever thought of himself as anything special. When we talked about his Medal of Honor mission, he would kind of laugh and say it was just a routine mission. He always said there were other missions that were really tough.”

“I didn’t consider the mission extraordinary,” Dethlefsen told Airman in 1969. “I had been up that way before, and I knew what to expect. I expected to get shot at a lot, and they shot at me a lot. I expected MiGs to be airborne and SAMs to be launched. And these things did occur. It was one of the more difficult of my 100 missions, and the ground fire was a little more intense.

“All I did was the job I was sent to do. It had been quite a while since we had been able to go to the Hanoi area. So while the weather held, we were able to do some pretty good work. It was a case of doing my job to the best of my ability. I think that is what we mean when we call ourselves professional airmen in the Air Force.”

Pardo’s Push

The two F-4s from Ubon that were lost on March 10 logged another dramatic story from Thai Nguyen. Before the strike flight reached the target, ground fire hit and damaged Capt. Bob Aman’s aircraft, but he and his backseater, 1st Lt. Bob Houghton, stayed with the formation. Over the target, they were hit again and began to leak fuel seriously.

Capt. Bob Pardo, with 1st Lt. Steve Wayne in the backseat, was hit as well. Pardo might have been able to reach a tanker, but Aman was going to run out of fuel before he could get to Laos, where he and Houghton could bail out with a reasonable chance of rescue. He was still over North Vietnam when he flamed out.

Pardo decided to push Aman to safer territory. He brought the nose of his F-4 into contact with Aman’s aircraft, but that didn’t work. He then told Aman to drop his tailhook. Pardo positioned the tailhook against his windscreen and pushed. Although the hook slipped frequently and had to be repositioned, that worked.

Aman’s rate of descent slowed. Then Pardo’s left engine caught fire. In any case, he was almost out of fuel himself. Both crews bailed out near the Laotian border and were rescued.

In the immediate aftermath of the incident, Pardo was in some trouble. Pilots were forbidden to attempt to push one airplane with another. However, the merit of it was recognized in the long run. In 1989, Pardo and Wayne were awarded the Silver Star for what had long since come to be known as “Pardo’s Push.” (See “Valor: Pardo’s Push,” October 1996, p. 8.)

John T. Correll was editor in chief of Air Force Magazine for 18 years and is now a contributing editor. His most recent article, “The Strategy of Desert Storm,” appeared in the January issue.