With the beginning of Operation Rolling Thunder (the bombing campaign against strategic targets in North Vietnam), the decision was made in March 1965 to interdict the North Vietnamese rail system, including the Thanh Hóa bridge. The Vietnamese, realizing the importance of the bridge, had set up an impressive air defense network, five air defense regiments being stationed in the area.
F-105Ds en route to North Vietnam.
First raid, first dogfight
The first — and largest — strike package to be sent against the bridge was codenamed 9-Alpha. Led by Korean war ace Colonel Robinson Risner, it comprised 79 aircraft, including 46 F-105 Thunderchiefs as the main strike force. Other types were 21 F-100 Super Sabres as AAA suppressors to attack ground-based guns, 14 F-100s acting as MiG CAP (combat air patrol) and two RF-101C Voodoos to do damage assessment, plus 10 KC-135 tanker aircraft. The F-100s were based in South Vietnam, while the others were based acrossThailand. Flights of four F-105s from Koran and Takhli would be air refueled over the Mekong River, then cross Laos to just south of the bridge. The bombers would continue east until over the Gulf of Tonkin.
Launched on April 3, 1965, the attack saw all strike aircraft deliver their payload. Sixteen of the F-105s carried a pair of Bullpup missiles, one under each outer wing pylon. This was an early combat use of early "smart" precision guided missiles that were guided by radio and joystick, requiring two passes to launch each of two missiles per plane before the evolution of laser-guided bombs which eventually felled the bridge late in the war. Capt. Bill Meyerholt observed as the missile streaked toward the bridge and made a good hit; when smoke cleared,there was no visible damage to the bridge. The tiny 250 lb warheads merely charred the massive structure. Crews grimly joked that Bullpups on the Dragon's Jaw were as effective as shooting BB pellets at a Sherman tank.
The other F-105s each carried 3 tons of explosives in the form of eight 750 lb (340 kg) bombs, more than B-17s had delivered over targets like Berlin. The first wave of bombs drifted due to a strong southwest wind. The last flight, led by Cpt. Carlyle S. "Smitty" Harris, scored hits on the roadway and superstructure. After 32 Bullpups and 1200 bombs had decorated the bridge with numerous hits, charring every part, the bridge did not fall, though traffic was stopped for a few hours. This was the only result of the raid, which had cost two aircraft — one F-100 (Lt. George C. Smith flying flak suppression) and one RF-101 — shot down.
Risner's Thunderchief was crippled by ground fire, but despite smoke in the cockpit, Risner continued to direct the strike before flying safely back to Da Nang.
To meet the raid, the VPAF had sent out two flights of four MiG-17PFs from Noi Bai airbase at 9:47. The original plan was for the first flight to act as decoy. The second flight never reached the strike force, as flight leader Pham Ngoc Lan spotted F-8E Crusaders from the USS Hancock covering the operation. The metal-finished MiG-17PF which would later be finished in a "snake" camouflage was an all-weather interceptor version of the MiG-17 first flown in 1951. Armed and 3 23mm cannons but no missles, it was a faster upgraded MiG-15 fitted with an afterburning engine, and a radar-ranging gunsight reversed-engineered from the F-86A  .  By comparison, the American Crusader was a daylight gunfighter capable of speeds of nearly twice the speed of sound, armed with both cannon and Sidewinder missiles. Lan dived to attack at about 1,000 feet, and fired at a range of 700 feet. His gun camera showed a blazing F-8 which he reported had crashed. At 10:15 wingman Lieutenant Phan Van Tuc fired on another F-8, claiming a second victory. Pilots Ho Van Quy and Tran Minh Phuong also opened fire on two F-8s, but were out of gun range. In the VPAF's evaluation, their success was due to proper preparation, using surprise and engaging only in close dogfights. While the US Navy records that all of the Crusaders returned, a plane flown by Lt. Cdr. Spence Thomas was so damaged it diverted to Da Nang and was written off as destroyed upon landing. That could make Lan's attack the first air-to-air kill not only by the VPAF's MiG-17s, but the first air victory of the conflict.The Navy recorded that an A-4 Skyhawk of Lt. Cdr. R. A. Vohden was lost to AAA; Vohden spent the rest of the war as a POW. After his victory, Lan found himself short on fuel. He elected to save his plane by making a hard landing by a riverbed in the Ke Tam valley (Nghe An province). He ironically was beseiged by locals who expected to find an American pilot until he showed his VPAF badge.
The VPAF had nevertheless demonstrated the ability to engage modern US fighters, and afterwards recognized April 3 as Air Force's Day. On the American side, the failure to drop any spans led to a new attack scheduled for the next day; it was expected by VPAF commanders. This time, 80 planes were engaged, including 48 F-105s, carrying only 750 lb (340 kg) bombs, as the inadequacy of the Bullpup had been fully demonstrated.
A North Vietnamese MiG-17 in 1972 from an American gun camera.
MiG-17s jump USAF F-105s
During the 4 April 1965 engagement, a tiny force of eight MiG-17s (half flying as decoys) from the 921st "Sao Do" (Red Star) Fighter Regiment (FR) was again given the daunting task of confronting a massive armada of modern American supersonic fighter-bombers.The 46 F-105 Thunderchiefs tasked as fast attack bombers were escorted by a flight of 21 F-100 Super Sabres daylight fighters from the 416th Tactical Fighter Squadron (TFS), 4Sidewinder-armed for MiGCAP, and 17 armed with 2.75-inch HVAR to suppress AAA batteries. Each flight was given a call sign. These included "Steel," "Iron," "Copper," "Moon," "Carbon," "Zinc," "Argon," "Graphite," "Esso," "Mobil," "Shell," and "Petrol." "Cadillac" flight conducted Bomb Damage Assessment, while the search and rescue included A-1 Skyraiders, call sign "Sandy," and HH-3 Jolly Green Giant rescue helicopters, call sign "Jolly Green."
The VPAF made ground-based AAA sites the first line of defence, with fighters attacking after ground gunners ceased fire. After taking off at about 10:20, the MiGs would break into decoy and attack flights. The leader was second-in-command Nguyen Van Tien, while Dao Ngo Ngu handled the ground control command.
|Tranh Hanh in wartime (dantri.com)|
Coming from clouds above, the MiG-17s tore past the escorts and dove onto the bomb laden Thunderchiefs, Communist flight leaderTrần Hanh spotted four F-105Ds at 10:30 starting to drop their bombs, ordering his wingman, Pham Giay, to cover his attack.  He fired at 400 meters, observing one F-105, piloted by Major Frank E. Bennett (355th TFW, KIA) fall in flames into the Gulf of Tonkin. The flight leader attempted to recover at Da Nang but had his controls freeze up within sight of the base. Ejecting, he was killed when his parachute failed to open before he struck the water and he drowned. As the Thuds turned to attack the MiGs, the MiG split into two groups on the north and south sides of the bridge. Supported by Tran Nguyen Nam, Le Minh Huan downed another F-105D, callsign Zinc 2 piloted by Capt. J. A. Magnusson. He radioed that he was heading for the Gulf if he could maintain control of his aircraft. Magnusson's aircraft finally bailed out 20 miles away over the Gulf of Tonkin near the island of Hon Me, and was eventually listed as missing and then killed after a 48-hour search. The USAF confirmed the two F-105 losses during that engagement.
The remaining fourth plane found himself in the sights of another MiG-17 who he could not shake. In desperation, he tried a snap roll which slowed his plane so that the MiG-17 over-shot him, as his captain had recommended. Finding himself on the MiG's tail, he was too surprised to attempt to shoot down the MiG with his gun. The fortunate survivor was briefed the day before about this maneuver by the captain from Nellis whoes name was the legendary John Boyd who would be a significant voice in the design of America's future dogfighters.
|416th TFS F-100Ds at Da Nang, 1965.|
After the quick success of downing two American fighters, the outnumbered North Vietnamese defenders faced a sky full of the remaining angered Thuds and Huns now fully alerted to their presence and turning their attention to the MiGs. Tranh Hanh ordered his flight to split into two groups. He and wingman Pham Giay stayed south side of the bridge, while Le Minh Huan and Tran Nguyen Nam flew to the north. Three F-100s from the MiGCAP, piloted by LTC Emmett L. Hays, CPT Keith B. Connolly, and CPT Donald W. Kilgus, all from the 416th TFS, engaged the MiG-17s. As the F-100s closed in, they hesitated to fire missiles which might hit their F-105s. The lead F-100 got a locking tone as he fired an IR guided Sidewinder air-to-air missile once he had a clear shot, but it passed above its target, while Connolly and Kilgus engaged with 20mm cannon.
Kilgus recognized what was Pham Giay's MiG just after it appeared out of the haze. He dropped his wing tanks and turned into the target that had just turned a 90 degree corner to face him. He shook off Tranh Hanh's second MiG which appeared as Giay overshot and missed him. Closing in from behind Giay, Kilgus closed in and pulled up his nose so that the four M39 20mm guns mounted under the belly of his airplane would just be visible winking to his target. Lighting his afterburner and using his height advantage, he accelerated and dived after the MiG at 450 knots. Kilgus recognized the Vietnamese pilot was pulling him into a game of chicken as both jets hurtled down towards waters of the Gulf of Tonkin and the lighter MiG should have been able pull out of a dangerous dive more quickly. Now headed nearly straight down, Kilgus armed his guns and took aim at the spot projected on the glass of his A4 radar-ranging gunsight.  While worrying about the rapidly falling altitude, he opened fire at 7,100 feet, observing puffs and sparks coming off Giay's vertical tail fin before losing visual contact as he pulled up, just barely clearing the Gulf of Tonkin.
Historian Don McCarthy later concluded he was certain Kilgus brought down the MiG-17. Aviation writer Larry Davis also records his that Kilgus' wing man also reported a kill, but it was denied by higher headquarters at 7th Air Force. Although not immediately reported that day, only Kilgus claimed and was credited with a probable kill. Based upon the report, the F-100s had obtained the first US aerial combat victories during the Vietnam War. If confirmed, Kilgus would have made the be the only air-to-air MiG kill by an F-100 during the conflict. , while it was assumed the other MiGs escaped.
MiG-17 flight leader and sole survivor Tran Hanh was credited with his confirmed F-105. His own plane narrowly escaped through hard manoeuvring, but he lost contact with ground control. Low on fuel, he opted to land at the nearby Ke Tam valley, but was detained the locals until he produced his VPAF badge. Hanh says that he saw his wingman, Le Minh Huan and Tran Nguyen Nam also shot down by F-105s.. Hanh probably confused the escorting F-100s for F-105s. As only one American pilot even claimed a probable kill, his other comrades may have instead collided or been hit by their own AA fire. Nevertheless, in exchange for their significant sacrifice, the North Vietnamese MiG-17s had scored their first confirmed aerial victories in jet-to-jet combat against supersonic fighters.
In North Vietnam, MiG-17 flight leader Tran Hanh became a national hero. What in retrospect might seem to be tactical draw after losing all of their defending fighters and three pilots, and viewed by anti-war activists as aggression against civilian targets, the action was celebrated as a "glorious victory over US aircraft to ensure the flow of war supplies to the south". For their part, anti-aircraft gunners received the Victory Order and the Military Exploit Order. On the 45th anniversary of the battle in 2010, Vietnam celebrated the downing of 47 US aircraft over the two days of the 454 sorties over two days that dropped 350 bombs on and around the bridge, calling it "the symbol of the Vietnamese people's will to defend their country...the Great Spring Victory to liberate the South and reunify the country." 
The raid had been carried out with great precision, but despite having been hit by more than 300 bombs, the
Thanh Hoa bridge still stood. As minor damage caused the circulation to be interrupted for a few days, it was seen as a modest success cost that had cost the US Air Force three F-105s. But U.S. Air Force chief of staff General John P. McConnell, was "hopping mad" to hear that two of America's most advanced F-105 Thunderchiefs had been shot down by slow, elderly left-over MIGs of the tiny 36-jet North Vietnamese air force. The subsonic MiG-17s had been in service for over 12 years since 1953, and was barely improved over the original MiG-15s that sparred with F-86 Sabres in dogfights over the Yalu River. By contrast, the F-105 which was on the drawing boards as the MiG entered service was two generations ahead (and the escorting F-100s one generation ahead). The Thud was the USAF's most advanced Mach 2 class fighter bomber with sophisticated navigation and radar systems which could be armed with sidewinder missiles and a bombload comparable to WWII bombers. But at slower speeds, the older MiG could out-manoeuvre any of its adversaries, and at a time when air-to-air missiles highly unlikely to actually destroy their targets, the cannons of the MiG were much more reliable, and deadly against F-105s which at the time were vulnerable to hits on systems such as hydraulics.
The losses to MiGs resulted in the subsequent replacement of the F-100 Super Sabre escorts with F-4 Phantoms. The incident would start a series of events that would lead to a reassessment of fighters better suited to close-in dogfighting. While the F-105 would finish off its service with a slightly better than even kill to loss ratio over MiGs, the large plane had been designed primarily to deliver bombs at low level rather than shoot down other fighters. Its replacement was the even larger Phantom which had been designed without any guns to fire missiles at stand-off ranges rather than tangle in turning dogfights. This experience would re-introduce the requirement that future fighters would need to be able to mix with MiGs on more equal terms and not just shoot missiles from a distance. This would lead to training programs such as Top Gun.
|Ill-fated F-111B Naval TFX was basically shot down by the elderly MiG-17 which it could not dogfight|
|F-14 was America's first purpose-built dogfighter in response to Mig-17s|
The expensive swing-wing F-111B which could not dogfight was dropped in favor of theVFAX which evolved into the F-14 Tomcat. The USAF would develop its own purpose-built FX supersonic air superiority fighter as theF-15 Eagle along with smaller teen-series fighters. The new fighters that came on line during the 1970s would dominate American airpower for the remainder of the twentieth century and inspire similar Soviet designs.