Hastily organized South Vietnamese airborne troops attempt a relief of An Loc in early April 1972.
In retrospect the Easter Offensive or something similar was bound to happen as both Hanoi and Washington pursued likeminded political-military strategies that placed them on a collision course. And while both rationally recognized that victory on the battlefield was beyond their grasp by 1972, each was still more than willing to give it one more try in the faint hope of delivering a coup de grâce. Thus, in one decisive stroke the war could be ended; no more dilly dallying in Paris. Both sides would come close to seeing these hopes fulfilled, but events beyond either’s control would conspire—as they often do in war—to snatch seeming battlefield victory from their hands at the last moment.
Hanoi’s opening gambit in the early days of the Easter Offensive surely looked like a winner. Saigon’s forces had taken a beating and given up considerable ground in the north of the country. Key government garrison towns in the south and the central highlands were soon cut off and besieged. American and South Vietnamese air power had staved off immediate defeat and bought time for Saigon, but how long they could maintain the effort was open to question. Moreover, with a paltry 95,000 Americans in country (nearly a quarter of which were Air Force personnel) there would be no U.S. ground combat units rushing to the rescue as they had done in 1968.1 The Thieu government was in serious trouble. Hanoi knew it and so did Washington.
While Nixon’s phased troop withdrawal from Vietnam was politically calculated to undercut his most vehement anti-war critics at home and allow time for full Vietnamization of the war, it also inevitably put Washington in a highly vulnerable military position and steadily weakened its negotiating leverage with Hanoi. Nixon’s military advisers had been deeply concerned that the approach would embolden the North once a theoretical crossover point was reached, whereby the United States would be too weak to respond effectively to Hanoi’s military provocations. Kissinger, for his part, saw it as undermining his ability to link American drawdowns to comparative North Vietnamese troop reductions in South Vietnam as a quid pro quo at the Paris talks. The launching of the Easter Offensive seemed to confirm these worse fears. During an early May meeting in Paris the North Vietnamese delegation refused to discuss a ceasefire and Le Duc Tho expressed his growing confidence that “the prospects for the North Vietnamese were looking good,”2 given the situation on the ground in South Vietnam.
Hastily organized South Vietnamese airborne troops attempt a relief of An Loc in early April 1972.
Hanoi deployed mobile anti-aircraft weapons, such as the 57-mm ZSU-57-2 (pictured), as well as 37-mm towed anti-aircraft guns and man-portable SA-7 surface-to-air missiles to South Vietnam for the first time during the Easter Offensive to counter low-flying American and South Vietnamese aircraft. (Photo National Museum of the U.S. Air Force)
This confidence, which surely reflected the popular view in Hanoi too, while well-founded given the early success of North Vietnamese forces, overlooked or downplayed several critical factors that would ultimately prove to be the North’s undoing and turn the tide of battle against it.
First, the ability of the North to mass more than 200,000 men along with tanks and heavy artillery for an offensive along three independent axes was indeed an impressive feat. Even more so that the preparations and staging of forces were accomplished in the face of persistent American and South Vietnamese interdiction efforts. While the initial weight of the onslaught quickly sent the South Vietnamese defenders reeling, Hanoi seriously underestimated the effort it would take to keep its forces supplied and reequipped for any extended campaign, especially as their lines of communication grew increasingly longer and susceptible to air attack.
North Vietnam Theater of Operations, 1972.
Second, the politburo’s decision to move away from a protracted guerilla warfare strategy by building a more conventional force structure aligned well with its belief that Vietnamization was foundering. Thus, it followed that Saigon’s forces would be unable to withstand the North’s might when locked into a conventional war. All this came at a cost, however, as the North Vietnamese were now increasingly dependent on the Soviet military pipeline to maintain this conventional force structure. Likewise, this new Soviet dependence and war strategy irritated the Chinese, who saw it as further indication of their waning political and military influence with Hanoi. Although Washington’s diplomatic efforts to drive a wedge between Hanoi and its key communist allies had yet to yield fruit, the potential consequences of American success also put the North’s new war strategy on dangerous footing.
Lastly, Hanoi not only underestimated the quickness and effectiveness of the American military reaction to their offensive, but also was overconfident in its ability to cope with the reaction. It terribly misread Nixon the man, the cold calculating politician who was willing to do whatever it took to ensure his legacy of bringing America peace with honor in Vietnam. And while certainly true that American military strength in Vietnam was at an all-time low in the spring of 1972 and had adopted a defensive and supporting posture, the U.S military presence in Southeast Asia still remained quite formidable. Air power topped the list. At the start of the year the United States still maintained a force of 385 aircraft (less than one-third strike) in South Vietnam and another 448 (nearly half of them strike) at bases in Thailand,3 while Navy aircraft carriers operating in the Gulf of Tonkin added an additional 200 aircraft to the total.4 It would be these air assets and their reinforcements that would be called upon to deliver Washington’s initial response to the North’s invasion. Ironically, because Nixon had few available options he was more than willing to engage in brinkmanship by pushing the limits of American air power. Or as Nixon bluntly put it, “The bastards have never been bombed like they’re going to be bombed this time.”5
Knocked-out and captured North Vietnamese T-54/55 tank in the aftermath of the battle for An Loc.
Destroyed and damaged North Vietnamese T-54/55 main battle tanks litter a road near Dong Ha in Quang Tri Province following an airstrike on April 12, 1972. When weather conditions permitted South Vietnamese and American strike aircraft and gunships pounded attacking enemy columns mercilessly.
The most pressing need was to beef up American air assets in Southeast Asia as quickly as possible. First to arrive in Da Nang, South Vietnam, in early April were U.S. Marine F-4 squadrons, VMFA-115 and VMFA-212 from Japan, along with the Air Force Phantoms of the 35th Tactical Fighter Squadron (TFS) out of Korea.6 The majority of additional planes, however, would come directly from U.S. Air Force bases in the United States under Operation Constant Guard that began on April 11. In less than five days three Air Force Phantom squadrons along with all their men and equipment were able to deploy from the United States to Thailand and were soon flying combat missions. Another 108 F-4s, two squadrons of C-130 transports, 16 KC-135 tankers, and nearly 100 additional B-52 heavy bombers would also soon arrive in theater.7 In all the Air Force would send the equivalent of 15 squadrons and 70,000 men to Southeast Asia in the opening months of the Easter Offensive, while the Navy would increase its air order of battle to an unprecedented six carrier air wings with more than 500 aircraft by May.8 In short order, the number of available American strike aircraft had more than doubled.
South Vietnamese and American artillery batteries fired off tens of thousands of high-explosive rounds in an attempt to stem the enemy advance.
Although still precarious after more than a month of fighting, the situation on the all three South Vietnamese battlefronts had slowly begun to stabilize by early May. Saigon and its military had apparently weathered the worst of the storm. Now it was time for the Americans to turn the tables on Hanoi. Accordingly, U.S. air commanders began gearing up for the largest aerial offensive since the end of Operation Rolling Thunder, one that pulled no punches and was designed to finally bring the war to an end.
General John Vogt, commander of the Seventh Air Force, during the height of the 1972 air campaign.
Even as the chaotic struggle in South Vietnam continued to play out, a new American bombing campaign against North Vietnam got underway on April 6. Codenamed Operation Freedom Train, the new effort targeted Hanoi’s supply lines, lines of communication, logistics facilities, and supporting military infrastructure from the DMZ northward to the 20th parallel to impede the vital southern flow of reinforcements, equipment, and supplies needed to maintain the momentum of the Easter Offensive. American tactical airstrikes and resupply missions in support of embattled South Vietnamese troops were still the number one priority, but U.S. air commanders dedicated considerable assets to Freedom Train operations as Nixon urged the newly appointed Seventh Air Force commander, General John Vogt, to be both “aggressive and imaginative” in his approach,9 the irony of which was probably not lost on Vogt, who was replacing a man in General John Lavelle whose aggressiveness and imaginative approach to bombing North Vietnam in the past had cost him his job.
The Marine base and airfield at Da Nang in the far north of the country once again became a central hub for supporting air operations both in South Vietnam and north of the DMZ following the start of the Easter Offensive.
The first airstrikes focused on attacking key logistics and transportation centers supporting the enemy offensive at Vinh and Dong Hoi, as well as against rail and road traffic along Highway 1. This would not be an easy task given the time Hanoi had to prepare and its greatly augmented air defenses throughout the southern panhandle. But the Americans had upped their game too. On April 9 a formation of 12 B-52 Stratofortresses supported by dozens of Air Force and Navy aircraft struck the railyard and an underground POL storage facility at Vinh in the first use of the heavy bombers over North Vietnam since October 1968.10 Following up this attack three days later, 18 U-Tapao-based B-52s struck the MiG airfield at Bai Thuong, about 25 miles west northwest of Thanh Hoa. One MiG-17 was destroyed on the ground and the runway was heavily cratered.11 On April 21 and 23, more bomber missions were launched against warehouse complexes near Thanh Hoa that involved 36 Stratofortresses out of U-Tapao air base, Thailand; one bomber was heavily damaged by an SA-2 missile during the April 23 attack and forced to divert to Da Nang for an emergency landing.12 Before the end of the month American pilots achieved a major psychological victory too. On April 27 Air Force F-4s from the 8th Tactical Fighter Wing (TFW) out of Ubon air base, Thailand used five 2,000-pound electro-optically guided bombs, or EOGBs, to collapse part of the western span of the Thanh Hoa bridge—the infamous Dragon’s Jaw bridge that had defied Rolling Thunder attacks for more than three years—and close it to traffic.13
Air Force F-4 Phantom squadrons at Ubon and Udorn air bases in Thailand would be stretched to the limit supporting air operations in both North and South Vietnam over the course of 1972.
Hanoi responded by forward-deploying MiG-21 fighters to Bai Thuong airfield in late April in the hopes of intercepting future B-52 raids and scoring a major victory by downing one of the big bombers. This resulted in Navy A-6 Intruders and A-7 Corsairs off the USS Coral Sea and USS Kitty Hawk targeting the airfield on several occasions and during a May 6 strike VPAF pilots rose to challenge the American attackers. In what would presage events to come, Navy F-4 Phantoms were able to shoot down two MiG-21s and one MiG-17 with Sidewinder air-to-air missiles that day.14 Following this setback, the MiGs at Bai Thuong were withdrawn to more protected bases around Hanoi.
In addition to these targeted strikes, Air Force and Navy aircraft patrolled the skies on armed reconnaissance missions (“armed recces”) south of the 20th parallel seeking out and attacking truck convoys, coastal and riverine watercraft, and ferreting out hidden supply depots and storage facilities.
While much of this new air offensive mimicked previous tactics and objectives of Rolling Thunder, the air threat in Route Package I—the operational area north of the DMZ up to Quang Khe—had risen enormously. Dozens of deadly SA-2 surface-to-air missile batteries were now deployed there, not only around important targets, but also right up to the DMZ to directly threaten allied air operations in the northern provinces of South Vietnam. Highlighting this danger, a U-Tapao-based B-52D flying an Arc Light bombing mission near Quang Tri on April 8 was seriously damaged by shrapnel from a missile explosion and was forced to make an emergency landing at Da Nang.15 Air Force efforts to take out these SAM sites met with mixed success and cost them several aircraft. The Navy also lost at least four planes to SA-2 missiles in the first four weeks of Freedom Train while attacking targets in the Dong Hoi area.16
Somewhat surprisingly given Nixon’s bellicose attitude, the new air effort against the North was off to a rather restrained start. So far nothing north of the 20th parallel in the North Vietnamese heartland was being bombed. This reflected a divided White House. Kissinger was deeply worried that any American bombing of the Hanoi-Haiphong area might not only jeopardize the Paris peace process, but could also cripple détente with the Soviet Union and the scheduled Strategic Arms Limitation Talks (SALT) summit in Moscow between President Nixon and General Secretary Leonid Brezhnev in May. Secretary of Defense Laird was also unenthusiastic, worried that an escalation might provoke Congress into slashing war funding at a critical time. However, others like deputy national security adviser Alexander Haig and members of the Joint Chiefs, wanted to send a strong message to Hanoi to stand down its offensive or else suffer the consequences. A compromise was reached in the form of Operation Freedom Porch Bravo, a limited oneday attack “against key logistics targets in the Haiphong and Hanoi complexes.”17
In the predawn hours of April 16 a formation of 17 B-52s from 307th Strategic Wing (SW) flying overnight from U-Tapao rained down some 460 tons of bombs from 34,000 feet on Haiphong’s main POL storage facility, igniting intense fires and triggering secondary explosions. Preceding the attack 15 Navy A-6 Intruders struck various SAM sites around Haiphong, while 20 Air Force F-4s laid a corridor of chaff—tens of thousands of small stripes of aluminum to confuse enemy radars and guidance systems—to screen the bombers as still other aircraft provided MiG combat air patrol and electronic countermeasure (ECM) support.18 As daylight broke over Haiphong a thick column of bellowing smoke could be seen by the sailors aboard the Kitty Hawk more than a hundred miles out to sea.19 A post-strike damage photo assessment indicated that 17 POL storage tanks, along with several nearby warehouses, railroad tracks, and 30 pieces of rolling stock had been destroyed in the attack.20
Andersen Air Force Base on Guam—“the Rock of the Pacific”—would become a major staging point for the B-52 bomber build-up as part of Operation Bullet Shot beginning in February 1972 and eventually would be home to nearly 150 B-52s. (Photo National Archives)
With an ability to lay waste to a 1.5-mile-long by half-mile-wide area, B-52 Arc Light bombing missions were extremely effective in breaking up massed troop formations and devastating attacking enemy forces. (Photo National Museum of the U.S. Air Force)
A second and third wave of close to 100 American aircraft soon followed during the day with strikes by Air Force F-4s and Navy A-7s on ten other targets. Hanoi’s main POL storage facility outside the city was hit by a 32-plane F-4 strike,21 while A-7s bombed Haiphong’s Cat Bi and Kien An airfields along with several warehouse and storage complexes in the Haiphong area. As expected, the strikes encountered heavy anti-aircraft fire and more than 250 surface-to-air missiles were fired, although most in a haphazard manner indicating the effectiveness of American countermeasures. Reacting MiGs of the 921st Fighter Regiment engaged Air Force F-4s near Hanoi, but ended up on the losing end; pilots with the 432nd Tactical Reconnaissance Wing (TRW) out of Udorn air base shot down three MiG-21s in aerial combat and a fourth crash while attempting to land. The Navy also destroyed three MiG-17s on the ground a Kien An.22 U.S losses for the entire operation were an Air Force F-105G Wild Weasel and a Navy A-7E downed by SA-2 missiles.23
The raids were deemed highly successful in both sending a message of American resolve and in destroying about half of the North’s POL storage and large amounts of stockpiled war supplies.24 Soviet reaction to the strike was surprisingly muted and SALT summit preparations continued to move forward. Nixon was pleased too, remarking to one of his advisers that “we really left them our calling card this weekend.”25
B-52D returns home to U-Tapao air base, Thailand, following a mission.
Nonetheless, neither the attacks on Hanoi-Haiphong nor the ongoing bombing south of the 20th parallel did little to change the minds of the North Vietnamese leadership in light of their successes on the South Vietnamese battlefield. Quang Tri city had fallen on May 1. An Loc was under siege and attacks in the central highlands against Kontum and Pleiku were still gaining momentum. With Hanoi feeling its oats and General Abrams reporting from Saigon that “it is quite possible that the South Vietnamese have lost the will to fight,”26 Nixon had little choice but to up the ante and unleash the full might of American air power against the North. Escalating the war at this point was a huge political and military gamble, but one Nixon felt he had little choice. The war needed to be settled and if Hanoi wouldn’t do that in Paris, then Washington would try to do it on the battlefield.
A key to stopping Hanoi’s offensive in the South lay in the ability of the United States to significantly slow the flow of men, equipment, and supplies to the battlefield, but past American air interdiction campaigns had been only marginally successful and the current Freedom Train operations alone were unlikely to produce the desired unless something dramatically different was done.
American military planners had long recognized the limitations of strategic interdiction as long as the North Vietnamese had an open-ended and uninterrupted source of supply from outside the country.27 In particular, Hanoi’s war machine was heavily dependent on resupply by sea. According to U.S. intelligence estimates, nearly 85 percent of the North’s imports—including practically all its oil shipments—came by sea, mainly from the Soviet Union and Eastern Europe.28 Moreover, virtually all of Hanoi’s sophisticated military equipment from surface-to-air missiles, fighter aircraft, and air defense equipment to tanks and heavy artillery flowed through Haiphong’s docks, making the port a critical chokepoint. Accordingly, a blockade of Haiphong and of other smaller North Vietnamese ports through the sowing of minefields would likely have a profound impact on the North’s ability to prosecute the war. It would also clearly signal Washington’s willingness to escalate the conflict if need be.
In response to the Easter Offensive the Navy would increase its presence in the Gulf of Tonkin by May 1972 to an unprecedented six carrier air wings comprising upward of 500 aircraft. (Photo Naval History and Heritage Command)
While militarily sound, a mining blockade of North Vietnamese ports was risky. “Neutral” communist-flagged ships would be put in direct danger and the mining could precipitate serious diplomatic blowback and at a time when Washington was seeking improved relations with Moscow, as well as the Kremlin’s help in advancing the Paris peace talks. It might also backfire and spur increased Chinese military aid to Hanoi to counter the American blockade. Nonetheless, Nixon bit the bullet. Relying on his firm determination to ensure American international credibility in a post-Vietnam world and to seize the opportunity to turn the tide of the war, Nixon authorized the mining on May 5 and the launching of a full-scale air assault against the North, in what Kissinger would later call “the finest moment of Nixon’s Presidency.”29
On the morning of May 8 six Navy A-7s and three Marine A-6s launched from the deck of the Coral Sea carrying at total of 36 MK-52 1,000-pound electromagnetic mines to sow the first minefield in the main shipping channel into Haiphong. Operation Pocket Money was underway. The plan called for a quick run-in with all nine aircraft dropping their mines in a single pass to avoid the anticipated heavy anti-aircraft fire from shore batteries. To maintain the element of surprise other Navy planes launched diversionary strikes away from Haiphong, while ECM jammers and fighter escorts screened the attack force. Two guided-missile cruisers, the USS Chicago and USS Long Beach, were also moved into position off the coast to provide radar warning coverage and defensive missile fire should North Vietnamese fighters react. Despite all these preparations, it would be a tricky mission that would test the skill and nerve of the pilots, who were all dropping aerial mines in combat for the first time.
F-4J Phantoms of VF-92 (foreground) and an A-7E Corsair II from VA-146 aboard the USS Constellation in May 1972 prior to the onset of Linebacker I. (Photo Naval History and Heritage Command)
An A-7E of VA-22 loaded with MK-52 sea mines on the eve of the mining of Haiphong harbor in May 1972. (Photo U.S. Navy) 46
A Marine A-6 from VMA-224 prepares to launch from the deck of the USS Coral Sea as part of Operation Pocket Money, the mining of Haiphong harbor on May 8, 1972. (Photo National Archives)
Skimming just 50 feet above the water to avoid radar detection and negate the SAM threat, the heavily laden jets made a beeline for the harbor channel shortly before 0900. Suddenly the Chicago’s radar picked up four enemy fighters heading southeast from Hanoi toward the strike force. The cruiser quickly fired a salvo of Talos surface-to-air missiles at the enemy formation, downing one MiG and forcing the others to scatter. Meanwhile, the strike force pressed on against light and not very accurate anti-aircraft fire and within the space of a few minutes all 36 mines were in the water without the loss of any aircraft. The mines would self-activate within 72 hours and nine ships took advantage of the warning to depart, but 27 others found themselves trapped in the harbor.30
Even before the pilots touched down on the deck of the Coral Sea, President Nixon was informing the American public of the mining of Haiphong harbor in a televised address and of his decision to begin a new, intense strategic bombing campaign against North Vietnam. Nixon noted he reluctantly took these actions in response to Hanoi’s continuing offensive in South Vietnam and its refusal to negotiate an acceptable settlement to the war. The time for talking was over. The next five months would witness an escalation of the air war that went well beyond any campaign heretofore and, this time, American air commanders were hell bent on getting it right.
In drawing up the new air offensive against the North, the Chairman of the Joint Chiefs, Admiral Thomas Moorer, sought to build on the momentum of Freedom Train operations to develop a hard-hitting campaign designed to once and for all destroy Hanoi’s war making capacity. In short, it was to be American air power unleashed. Linebacker, as the new operation was named, would be a decidedly marked departure from the past: no White House micromanagement, no complex bombing or targeting restrictions. It would be first and foremost a military operation, but one with a single, clear singular political objective of ending the war for the United States.
The bombing campaign began in earnest on May 10 with the first Linebacker missions flown against targets in the Hanoi-Haiphong heartland and, as if to underscore the high stakes involved, that day’s events would dramatically signal the start of the most intense and ultimately decisive period of aerial combat of the entire Vietnam War.
The USS Constellation’s Carrier Air Wing 9 (CVW-9) opened the campaign with 17 of its A-6s and A-7s attacking Haiphong’s main POL storage facility (the same one that had been heavily damage by B-52s during Operation Freedom Porch Bravo) with more than 50 tons of MK-82 500-pound bombs, leaving the facility badly damaged and in flames.31 The strike was preceded by F-4 flak suppressors and A-7 Iron Hands—SAM suppression missions—engaging anti-aircraft positions and SA-2 missile batteries. Additional Navy F-4 Phantom fighters provided a combat air patrol screen to the west of the city. Two more waves of some 60 Navy aircraft soon joined in the air assault on Haiphong. The Constellation’s planes busied themselves with cratering the downtown railyard, while aircraft from the Kitty Hawk were able to drop a span of the main highway and rail bridge out of the city.32 In all the Navy would fly 176 attack sorties that first day of Linebacker without a single aircraft loss; one RA-5 Vigilante aircraft flying a post-strike reconnaissance mission did suffer serious damage from SA-2 missile shrapnel.
Chairman of the Joint Chiefs, Admiral Thomas Moorer (far left) along with the other Joint Chiefs and Secretary of Defense Laird in January 1973. Admiral Moorer was tasked with developing a strategic interdiction bombing campaign to dramatically cut the flow of men and matériel southward and to curtail Hanoi’s war-making capacity by striking at the North’s heartland in May 1972. (Photo Department of Defense)
Meanwhile in the skies over Hanoi some 55 miles to the west, the Air Force was getting into the act in a big way by sending 117 attack and support aircraft into the fray. The main strike force was composed of 32 F-4 Phantoms from the 8th TFW carrying an array of precision guided and conventional munitions, while 12 F-105G Wild Weasels provided air defense suppression and 28 Phantom fighters from the 432nd TFW out of Udorn, Thailand flew air cover for the strike force.33 In what would become a familiar routine dozens of other aircraft were tasked with providing ECM, communications, early warning, reconnaissance, rescue, and refueling support for the attack. Their targets for that morning were the Paul Doumer Bridge and the railyard at Yen Vien, just to the east and northeast respectively of downtown Hanoi. As one of the best well-defended cities in the world the attackers would be flying into the belly of the beast.
The USS Constellation would make her sixth and final combat deployment of the war beginning in October 1971 along with the squadrons of Air Wing 9. The wing’s F-4s would score nine air combat victories, including five by the war’s first ace, Lieutenant Randall Cunningham. (Photo National Archives)
The Navy’s advanced all-weather A-6 Intruder would prove to be highly capable of delivering large payloads against heavily defended North Vietnamese targets both day and night.
Knocking out the mile-long Paul Doumer Bridge was a top priority. The mile-long rail and highway bridge spanned the Red River linking downtown Hanoi with its eastern districts and was the city’s only rail link to Haiphong, as well as being the only rail crossing of the river for southbound traffic within 30 miles. It had been successfully bombed and disabled by the Air Force during Rolling Thunder in August 1967, but had since been repaired and was once again fully operational. Just as before it was heavily defended; more than a hundred anti-aircraft guns ranging up to 100-mm ringed the bridge, multiple SA-2 missile batteries sites covered the skies above, and three major MiG fighter airfields were within a few minutes’ flying time. But in stark contrast to the attack nearly five years before that required some 60 planes and nearly 100 tons of ordnance, this time only 16 F-4s armed with 29 tons of precision guided bombs would be tasked with doing the job.34
Preceding the strike groups, eight F-4s released chaff along the flight path, while another eight Phantoms from the 432rd TRW flew combat air patrol to counter the anticipated MiG reaction. In addition, each incoming strike group was accompanied by four F-105G Wild Weasels for SAM and flak suppression and four F-4 fighters providing strike escort duties.35 Anticipation weighed heavily on the pilots and crews, who were expecting a tough fight on their return to Hanoi. They were not to be disappointed.
By mid-morning Major Robert Lodge and his fighter screen found themselves engaged in a twisting and turning dogfight with at least six North Vietnamese MiG fighters northwest of Hanoi. Initially the Americans got the better of the fight, downing three MiG-21s with Sparrow AIM-7 air-to-air missiles.36 But then a pair of MiG-19s from the 925th Fighter Regiment out of Yen Bai jumped Lodge, sending his Phantom spiraling out of control in a hail of 30-mm cannon fire. Lodge was killed in the attack, while his weapons system officer Captain Roger Locher ejected and spent an amazing three weeks on the ground evading capture before finally being rescued. Meanwhile, the Paul Doumer strike force pressed on from the south of the city, evading barrages of SA-2 missiles—part of around 100 fired that day—as they approached their target. Anti-aircraft fire was less than expected and all 16 F-4s were able to release their loads on target. Even though all four of the 2,000-pound EOGBs missed, the other dozen laser-guided bombs (LGBs) scored hits and were able to severely damage the bridge. The next day General Vogt sent a single flight of four Phantoms armed with 2,000- and 3,000-pound laser-guided bombs to finish the job, successfully dropping three spans of the bridge and rendering it inoperable until the end of the war.37
The single-seat A-7 along with its two-man A-6 counterpart would form the backbone of the Navy’s air strike arm force during Linebacker I & II. (Photo Naval History and Heritage Command)
An A-7E from the “Dambusters” of VA-195 unloads its bombs on the Hai Doung bridge east of Hanoi on the opening day of Linebacker I. (Photo Naval History and Heritage Command)
Haiphong’s shipyard and warehouse complexes come under Navy air attack on May 17, 1972. (Photo National Archives)
Explosions rock a large POL storage site northwest of Vinh after being struck by aircraft from the USS Kitty Hawk. (Photo Naval History and Heritage Command)
The other target that morning would be the nearby railyard at Yen Vien, which was an important transportation and logistics hub for supplies arriving from China. Sixteen Phantoms from the 8th TFW armed with conventional 500-pound bombs were given that assignment.38 Hot on the heels of the Paul Doumer strike group, the second group of 16 F-4s and their escorts pressed northward to attack and successfully crater the main railyard at Yen Vien with 36 tons of bombs. Once again the attackers were able to evade enemy surface-to-air missiles and anti-aircraft fire, but a lone MiG-19 was able to ambush and shoot down an F-4E escort as it was leaving the target area. Both the pilot and weapons officer were killed.39
The day was far from over however. In the early afternoon, 90 naval aircraft launched an attack against the strategic town of Hai Duong midway between Haiphong and Hanoi. It was home to a major railyard, vital rail and highway bridge crossing, and POL storage facility. Several flights of A-7 Iron Hands struck nearby SAM sites, as other Corsairs and Intruders off the Constellation began the assault by unleashing a torrent of MK-82 bombs on the railyard. They were soon followed by a second and third wave from the Coral Sea and Kitty Hawk. Meanwhile, dozens of F-4s provided flak suppression, served as strike escorts or flew MiG combat air patrol to counter the anticipated enemy fighter threat.
The Navy fighter pilots would not have to wait long and soon the Chicago’s combat information center that was responsible for tracking and reporting enemy aircraft movements (call sign “Red Crown”) was transmitting a flurry of enemy radar contacts. In short order, nearly two dozen VPAF MiG fighters would be airborne and seeking out the Americans. As CVW-9’s CAG, Commander Gus Eggert, grappled with coordinating the strikes on Hai Duong from overhead, the wing’s combat air patrol broke to intercept the incoming MiGs. What quickly ensued in the skies east of Hanoi was the largest aerial battle of the war, involving no less than 45 American and North Vietnamese aircraft. When it was all over, seven MiG-17s had been brought down by U.S. missile fire without the loss of a single Navy fighter. Notably, Lieutenant Randall Cunningham and his radar intercept officer Lieutenant (j.g.) William Driscoll of VF-96 would rack up three kills that day, pushing their total to five enemy aircraft and thus become the first aces of the Vietnam War.
The day was not yet done for the Navy and by the late afternoon CVW-9 conducted its third alpha strike of the day against harbor facilities at Hon Gai, some 20 miles northeast of Haiphong, as planes from the Coral Sea’s CVW-15 simultaneously struck the rail and highway bridge at the port of Cam Pha farther to the east. Both were lightly defended targets and only two MiGs made a brief appearance before retiring without engaging the attackers. The most noteworthy aspect of these strikes were two wayward MK-82 bombs at Hon Gai hitting and seriously damaging a Soviet ship and killing one of the ship’s crew.40 All planes returned safely to their ships by early evening. This brought an end to the first day of Linebacker with American pilots flying more than 400 sorties against the North Vietnamese heartland, leaving in their wake destroyed or heavily damaged rail and highway bridges, cratered railyards, and smoldering storage facilities. Eleven MiGs had been shot down in aerial combat at the cost of two Air Force F-4s; two other Navy Phantoms were lost to SA-2 and anti-aircraft fire and a third was so severely damaged that it was written off.41
An A-7E from VA-147 catching the wire aboard the USS Constellation after successfully completing its mission. (Photo Naval History and Heritage Command)
Lieutenant Randell Cunningham (left) and Lieutenant (junior grade) William Driscoll (right) of May 10, 1972 fame hold replica F-4 Phantom models as Secretary of the Navy John Warner and Chief of Naval Operations Elmo Zumwalt look on. (Photo Naval History and Heritage Command)
Improving the accuracy of aerial bombing has been a constant quest since aircraft were first equipped with bombs. Through advances in technology, bomb design, and pilot training the overall level of bombing accuracy as calculated by circular error probable or CEP—the area described by a circle with the target at its center within which 50 percent of the bombs dropped will fall—had steadily improved from 1,000 feet by the end of World War II to 420 feet at the start of the Vietnam War. For real precision bombing, however, this was not good enough. The bombing of North Vietnam during Rolling Thunder underscored the American need for vastly improved weapons accuracy against well-defended fixed targets, such as bridges, power plants, communications sites, or those high-value targets located close to large civilian populations.
The first smart bomb—actually designated an air-to-ground missile—used in Vietnam was the Navy’s AGM-62 “Walleye” in 1967. It was a free-fall munition with a large 825-pound warhead that relied on a television tracking system to lock onto the target. The “fire and forget” Walleyes had some notable successes during Rolling Thunder, particularly their use against Hanoi’s downtown thermal power plant in May 1967. Nonetheless, the weapon required a sharp level of contrast to lock onto the target and was often foiled by poor weather. It was also expensive at $35,000 each. The proven concept, however, pushed the Air Force to develop its own electro-optical guide bomb, called Hobo (Homing Bomb System), with improved accuracy and a less costly at $17,000 per copy.
The big breakthrough in smart bombs, however, came with the advent of laser-guided bombs in the late 1960s following a partnership between the Air Force and Texas Instruments to develop a weapon with a maximum CEP of 30 feet. Thanks to the personal efforts of Colonel Joseph Davis, Jr., vice-commander of the Air Proving Ground at Eglin Air Force Base, and Weldon Word, a Texas Instrument engineer, the laser kit concept was born. The kit consisted of a seeker and guidance components that could then be attached to standard conventional bombs and thus, turning them into laser-guided munitions. The specially made seeker head was attached to the nose of the bomb, while the guidance system and control fins were adapted from a Shrike missile and attached to the rear of the bomb. Once released the bomb flew a zigzag course to the target as the fins made corrective adjustments every few seconds to bring the laser reflection back to the center of the seeker head’s field of view.
The laser-guide bombs required two airplanes working together. The first acted as the designator to focus a tight laser beam on the target, painting it continuously and reflecting back outward a cone of laser energy called the “basket.” The second plane would then drop its bomb into the “basket” allowing the bomb’s seeker head to lock onto the laser illumination and home on the target. After successful proof of concept testing at Eglin, a contract was awarded to Texas Instruments in 1967. The Air Force designated the initial version of its laser-guided bombs or LGBs as Paveway.
Combat testing took place in Vietnam in mid-1968 by the 8th TFW at Ubon Air Base in Thailand with good results. The original laser designator device, fabricated by two Air Force officers at Eglin, was mounted on the left canopy rail of the rear cockpit of an F-4 Phantom. It was called the “Zot” by air crews, after the sound effect for the lightning-fast anteater’s tongue in the then popular B.C. comic strip. The beam proved sharp and accurate for a distance of more than five miles, but the designator aircraft was required to orbit the target in a left bank of almost 40 degrees at an altitude of 12,000 feet while fixing its beam on the target. Any number of aircraft could then drop their LGBs into the basket. The designator aircraft, however, needed to hold its illumination on the target until the bombs hit (about 30 seconds after release).
While both standard 750-pound MK-117 and 2,000-pound MK-84 bombs were used in combat testing, the more aerodynamic shape of the MK-84 was more amenable to attaching the laser kits and produced an impressive CEP of 20 feet on a consistent basis, with one in every four scoring a direct hit. At 2,000 pounds the MK-84 also produced a much bigger punch and was significantly cheaper— at $3,000 each—than the Walleye and Hobo EGOB options. The end of Rolling Thunder preempted Paveway LGBs use in North Vietnam, but they were used selectively in South Vietnam and Laos over the next four years.
Considerable progress on improving the Paveway system and pilot training was made during the bombing hiatus. By 1972 the Zot box was beginning to be replaced by the Pave Knife laser designator pod. This pod was on a gimbal which swiveled around to keep the laser beam on target, freeing the designator plane to maneuver at will and reduce its vulnerability. Furthermore, the plane could now also drop bombs as well as illuminate the target.
At the time of the 1972 Easter Offensive the Air Force, however, had only seven F-4s equipped with Pave Knife pods so it had to carefully husband this resource. LGBs were used judiciously against the most important and sensitive targets, with Pave Knife being a necessity for the high-threat environment around Hanoi and Haiphong. LGBs produced impressive results. From February 1972 to February 1973, the Air Force dropped more than 10,500 LGBs, resulting in 5,100 direct hits and another 4,000 had a CEP of 25 feet. A later study found that LGBs in Vietnam were “100 to 200 times as effective as conventional bombs against very hard targets.” The era of the smart bomb was well on its way.
Source: Adapted from “The Emergence of Smart Bombs,” Air Force Magazine, March 2010.
The remaining weeks of May saw the air campaign steadily gain momentum and intensify as the Americans stepped up their interdiction efforts against the North Vietnamese transportation and logistics network in the face of dogged resistance by the North’s defenders.
Air Force F-4s refueling on their way north. Phantoms operating from bases in Thailand would play a major strike role during Linebacker I, delivering both conventional and laser-guided bombs.
The critically important Paul Doumer Bridge over the Red River east of downtown Hanoi fell under the weight of Air Force laser-guide bombs in the opening days of the air campaign and would remain out of service until the end of the war. (Photo National Museum of the U.S. Air Force)
By mid-month Pocket Money operations had successfully sowed additional minefields of primarily MK-36 DST 500-pound magnetic mines outside the smaller ports Cam Pha and Hon Gai north of Haiphong, as well as in the important river estuaries down the coast at Thanh Hoa, Vinh, Quang Khe, and Dong Hoi. This forced the North Vietnamese into the time- and labor-consuming process of unloading ships into shallow draft boats or barges, thus increasing the unloading time for a 5,000–6,000-ton ship to more than a month42 and making the small boats and barges vulnerable to attack by U.S. aircraft. This effectively cut the movement of supplies by sea (most notably Soviet oil imports) into the country and made the North increasingly dependent on land routes from China. More than 11,000 mines would eventually be sowed by Navy pilots over the remainder of the year to keep the fields active by periodic reseeding.43
As with Rolling Thunder major rail and highway bridges were high-priority targets for Linebacker missions. Those bridges serving as conduits for military equipment and supplies flowing southward from Hanoi and those at key points along the rail and road links to China topped the list. On May 13, the Air Force returned to finish off the infamous Dragon’s Jaw bridge at Thanh Hoa that it knocked out of service in late April. This time 14 F-4s from the 8th TFW armed with 2,000- and 3,000-pound LGBs, as well as conventional MK-82s unleashed almost 69 tons of ordnance on the bridge, quickly sending the entire western span into the Song Ma River.44 Periodic attacks throughout the remainder of the year prevented its repair and kept it out of service until the end of the war. Likewise, several more key rail and highway bridges along Highway 1 from Vinh southward were also knocked out by Navy strikes in the opening weeks of the campaign.
An F-105G Wild Weasel armed with two AGM-45 Shrikes on each wing and one AGM-78 Standard ARM (left wing); wing fuel tank on right used to balance AGM-78; QRC-380 jamming blisters on fuselage. The Wild Weasels played an essential role in suppressing North Vietnamese air defenses and thus allowed following strike aircraft a clear pathway to their targets, earning them the motto of “First in, last out.” (Photo National Museum of the U.S. Air Force)
EB-66 jammers from the 42nd Tactical Electronic Warfare Squadron at Korat comprised a vital part of Air Force strike packages by seeking to neutralize the North Vietnamese surface-to-air threat. (Photo National Museum of the U.S. Air Force)
Meanwhile, in the far north, Air Force laser-guided bombs soon destroyed 13 rail bridges along the northeast and northwest rail corridors that linked Hanoi to the Chinese border.45 Several bridges, such as the important Lan Giai rail bridge along the northeast line, located inside the 30 nautical mile Chinese buffer zone were struck for the first time in the war. On May 25, 20 F-4s from the 8th TFW bombed the Lan Giai bridge, successfully dropping six of its eleven spans using LGBs and EOGBs.46 Navy Intruders and Corsairs were also able to disable four other rail bridges between Haiphong and Hanoi during the month as well.
So far Linebacker was off to a good start for the Americans with the Air Force and Navy flying over 6,000 sorties in May. Many key targets had been successfully struck, new countermeasures, precision-guided munitions, and tactics appeared to be working well, 27 VPAF MiGs had been shot down in combat, and the strategic interdiction effort was already beginning to have an impact on Hanoi’s offensive in the South. This did, however, come at a cost—20 U.S. aircraft (eleven Navy and nine Air Force) were lost, nine pilots and crewmen were killed, and another 12 were captured.47 And while undoubtedly pleased with the initial success of the campaign, air commanders and pilots alike knew tough times were still to come, because Hanoi was not about to capitulate without a fierce fight.