Invading North Vietnam

Between 1964 and 1967, North Vietnam and the United States each poured increasing numbers of troops into the war to determine South Vietnam’s political future. U.S. commanders sought new ways to ratchet up military pressure on Hanoi. They intended to intensify the fighting inside the South as well as raise the stakes, “doubling down” by attacking more aggressively in enemy territory to break communist leaders’ will to continue the war. Planners identified options that included intensified bombing of the North, mining harbors and coastal waters, interdicting the Ho Chi Minh Trail in Laos with allied ground forces, and invading North Vietnam. 

One invasion plan, Operation Butt Stroke, was developed by Military Assistance Command, Vietnam (MACV), in 1967. (The unfortunate name refers to a melee technique of using the butt of a rifle to attack an opponent.) This little-known operational “path not taken” underscores a critical deficiency in allied counterfire capability seldom noted in the war’s historiography, and it highlights the self-inflicted limits of the U.S. attrition strategy. 

The Tactical Problem

The military situation prevailing along the inaptly named Demilitarized Zone (DMZ) separating North and South Vietnam drove the development of MACV’s invasion plans. South Vietnam’s five northern provinces, collectively known as “I Corps” for the Republic of Vietnam Army (ARVN) corps responsible for them, were the scene of the conflict’s worst fighting, including a July 1966 invasion by the North Vietnamese Army (NVA).¹

By April 1967, intelligence analysts noted three NVA divisions arrayed along I Corps’ northern border, with a fourth located within 20 miles and another pair four to ten days’ march away. Facing them were one ARVN division and three infantry battalions of U.S. Marines.² The communist campaign that soon commenced dwarfed the intensity and lethality of the previous year’s battles. Fighting broke out across the whole of the DMZ, from the sea to the hills around Khe Sanh.³ Throughout the spring and summer, the NVA’s artillery attacks intensified; by the end of the year, the communists had fired 42,000 shells along the border. Seventy-five to 100 cannon within or just north of the DMZ delivered almost half of them. Mortars and rockets, mostly fired from positions inside South Vietnam, accounted for the rest. By midsummer, the rain of fire prompted III Marine Amphibious Force (III MAF) to conclude that “extraordinary measures must be taken.”⁴

Butt Stroke

Planners at MACV, U.S. Pacific Command, and the Pentagon proposed an amphibious assault be one of those measures. Marine Corps leaders chafed under the policy constraints that prevented U.S. ground forces from crossing the 17th parallel to eradicate the enemy’s artillery. MACV plans created in 1964 had envisioned establishing an amphibious lodgment near the port of Vinh in North Vietnam. From this enclave, allied forces would either attack key inland political, economic, and military targets; hold and defend them indefinitely to pressure enemy leaders to withdraw their forces from the South; or withdraw upon completion of the intended destruction within the beachhead.⁵ 

By 1967, MACV planners had more modest goals. They simply sought to eliminate the NVA artillery threat, capture or render unusable enemy supply depots near the DMZ, and destroy as many communist forces as they could. After considering larger and smaller invasions, MACV eventually settled on a midsized scheme, Butt Stroke, to neutralize enemy forces operating from the sanctuary north of the Ben Hai River.⁶

The operation would have placed four to seven allied maneuver brigades ashore in North Vietnam near the port of Dong Hoi, 30 miles north of the DMZ. Once established, the landing force would attack south along the coast. It would link up with ARVN I Corps and III MAF forces that were to attack into the DMZ to fix NVA units arrayed there. The operation would conclude once the landing force completed its destruction of enemy forces and supplies in zone and crossed back into South Vietnam. 

MACV planners anticipated the scheme of maneuver, an envelopment of the four NVA divisions in the region, would take 45 days to marshal, rehearse, and move the assault force, and then 30 to 60 days to eliminate enemy troops and bases between the landing beaches and the border. All told, the operation would have stretched from May to August 1968.⁷

Butt Stroke was to be an operational-level raid, with a desired end state and planned withdrawal (albeit one measured in weeks rather than hours or days). The maximum assault force comprised an airmobile division headquarters directing two air assault brigades (likely from the 1st Cavalry Division); one brigade of U.S. paratroopers; one U.S. Marine division headquarters controlling a regimental landing team with an attached tank battalion and the 9th Marine Amphibious Brigade from Okinawa; and one South Vietnamese division headquarters managing one ARVN airborne regiment and one Vietnamese Marine regiment. The staff assessment concluded that, given sufficient fire support, fewer troops could suffice, but necessary force ratios depended on whether the enemy elected to fight or flee.⁸ Fighting promised a target-rich environment. But even if the NVA chose (and managed) to evade MACV’s intended trap, it still stood to lose much of its heavy weapons, equipment, and supplies in a sector previously off-limits to allied ground attacks. 

Support for the planned invasion, though limited by World War II standards, rivaled that required for the 1950 Inchon assault in Korea and exceeded any forcible-entry operation executed since.⁹ The U.S. Navy anticipated employing 78 amphibious ships accompanied by 20 to 30 naval gunfire vessels. Plans called for several aircraft carriers to provide close-air and antisubmarine support, in addition to Air Force and Marine Corps tactical aircraft flying from airfields in South Vietnam and Thailand.¹⁰

Air and naval forces also would interdict enemy reinforcements. Light carriers would ferry Army helicopters to launch points off the coast. Corps artillery included three battalions of cannon and three of antiaircraft guns and missiles. Some three battalions of Army engineers would enable movement off the beach, repair the roads south, block avenues of approach from the north and west, and assist in crossing the three major rivers between the landing sites and South Vietnam. The plan required swift movement inland, followed by a rapid attack south to friendly lines, so planners envisioned only small supply dumps ashore. Logisticians expected to resupply the fast-moving columns by air and sea, with landing craft meeting the spearheads along the route.¹¹

As with all joint and combined operations, command-and-control issues proved critical for the Butt Stroke plan. Ground, air, and naval components agreed to employ the traditional tenets of U.S. amphibious doctrine: Commander, Seventh Fleet, would lead the joint expeditionary task force until control of operations ashore passed to the landing force commander. The ground command element would be a provisional corps headquarters provided by the U.S. Army (likely because MACV commander General William C. Westmoreland did not trust the Marines to direct corps-level mobile operations).¹² A contentious aspect of the plan focused on whether aviation operations above North Vietnam in support of the raid would be controlled by III MAF’s air wing or Seventh Air Force.

Assessing the Plan

Butt Stroke promised a daring strike into one of the enemy’s major logistic staging areas that also held a deadly concentration of his artillery. It is unknowable whether the NVA would have retreated, as it did in the 1969–70 incursions in the A Shau Valley and Cambodia, or fought tooth and nail to protect its supply lines, as it did against ARVN’s 1971 attack into Laos to disrupt the Ho Chi Minh Trail. North Vietnamese troops performed best in well-rehearsed, set-piece operations. In a mobile campaign, planners anticipated the defending NVA would suffer the same defeat its best divisions had experienced over the preceding two years in South Vietnam when pitted against elite allied forces backed by strong firepower. 

Amphibious assaults often entail races to build up combat power. The landing force seeks to put ashore enough troops and supplies to accomplish the mission before defenders can react with sufficient strength to defeat the invasion. MACV’s proposed operation aimed to win that race, but it is unlikely the assault would have achieved operational surprise in a war where Viet Cong headquarters in remote jungles received advance notice of B-52 strikes launched from bases in Guam. Marshaling the troops, ships, planes, and supplies required for the landing would not have gone unnoticed by the NVA and Viet Cong or their Soviet and Chinese allies. Nonetheless, force, space, and time considerations conspired against a successful defense. Communist divisions were half the size of their U.S. counterparts and had far less supporting fires; prepared defenses were not oriented to oppose an attack from the sea or the north; and it would have taken several weeks to bring in additional divisions from regions farther north and mass them against a moving foe.¹³

An important question for planners was how the People’s Republic of China would respond to an invasion. Postwar Western analysts often impute inevitable Chinese intervention, as in the Korean War, in reaction to any U.S. initiative to broaden the war. Available evidence is not conclusive, but based on the intelligence available at the time, Westmoreland believed that heavier bombing, mining the North’s harbors, or an operation such as Butt Stroke would not have triggered a major Chinese or Soviet military response.¹⁴ His planners estimated that the clearly limited nature of the amphibious assault, including its attack back toward the DMZ, would dissuade Beijing and Moscow from committing their own ground combat forces.¹⁵

A Defense Intelligence Agency (DIA) assessment of possible Chinese response to a different, larger invasion plan (Operation Mule Shoe) forecast a high risk that China would introduce ground combat forces into North Vietnam but not engage U.S. units. The DIA predicted the Soviet Union would condemn the U.S. action and “increase its deliveries of military items to [North Vietnam] as tangible evidence of its support of Hanoi.” MACV planners believed China would not see the shallow incursion as a serious threat to the Hanoi regime and that Beijing could be deterred from intervening by “a strong U.S. resolve to retaliate against key areas of China.” U.S. commanders and their staffs concluded that the risk of Chinese intervention “must be accepted if the destruction of major enemy forces in and adjacent to the DMZ is to be achieved.” Moreover, they believed the operation would be acceptable politically at home and abroad “if keyed to the flagrant NVA violations of the DMZ.”¹⁶

A Little Known Weakness

MACV’s willingness to consider bold strokes such as invasion reveals much about an unappreciated aspect of the war. The U.S. military lacked an effective and efficient counterartillery capability in 1967. It employed ground reconnaissance, aerial observation, flash and sound ranging, radars, and shell reports to determine the origin of incoming fire.¹⁷ But target acquisition, precision fires, and damage assessments proved insufficient in the counterfire fight along the DMZ. 

III MAF orchestrated heavy and sustained artillery, naval gunfire, tactical air, and B-52 strikes from September to December 1967. Combined, they delivered 42,495 tons of bombs and 743,467 shells against the NVA artillery, destroying 39 guns and damaging 35 more, according to a contemporary damage assessment.¹⁸ If accurate, this amounted to between two-thirds and all of the enemy’s artillery immediately north of the DMZ. But subsequent studies concluded that counterfire assessments were frequently inaccurate and too slow to optimize reattacks. Moreover, NVA gunners shifted their pieces frequently and were most active during times that obviated allied technical advantages (daylight to spoil flash ranging, fog and rain to counter aerial observers, etc.). They also fired from fortified positions, often turning bomb craters into gun positions seven feet deep, with ammunition and personnel bunkers that only a direct hit from a large caliber shell or bomb could destroy.¹⁹

General Westmoreland called the attacks on the enemy’s frontier artillery “the heaviest concentration of firepower on any single piece of real estate in the history of warfare.”²⁰ But South Vietnamese and U.S. soldiers near the DMZ continued to suffer from artillery fire for the rest of the conflict. Nearly half the allied casualties in Quang Tri, the bloodiest province of the war, resulted from indirect fire.²¹ Then–Brigadier General Louis Metzger, deputy commander of 3d Marine Division, concluded that the allied counterfire effort simply did not work and that proficiency with these tactics and techniques had atrophied since 1945.²² Given the persistence of this lethal artillery threat, it is no wonder that commanders desired to erase it with a ground attack on the enemy’s elusive firing positions. 

Insights

The 1967 amphibious plans for invading North Vietnam reveal several important insights about the war. While the tactical justification for the raids was to eliminate the enemy’s artillery threat, the operational rationale supported the war’s larger attrition strategy. These plans, designed to destroy as many units, weapons, and supplies as possible, were a bid to break northern leaders’ will to continue the war. 

Second, artillery—the 20th century’s great battlefield killer—proved difficult to suppress, despite substantial U.S. technical advantages over NVA gunners.²³ Service, academic, and popular histories of the war have not emphasized this fact. Even a successful Butt Stroke campaign would have provided only temporary relief from the scourge of indirect fire along the DMZ. Hanoi simply could have replaced destroyed artillery units, like its serially wrecked infantry formations, with fresh peasant recruits and new guns provided by its communist superpower sponsors. 

Third, both North Vietnamese and U.S. military leaders arrived at similar solutions to breaking the prevailing tactical stalemate in 1967. Each side recommended intensifying the war in the following year. Timing, as always in military affairs, proved crucial. General Westmoreland projected conducting an amphibious raid, in lieu of or in conjunction with efforts to block the Ho Chi Minh Trail in Laos, in May 1968. Even if the Johnson administration had approved the invasion, its execution would have lagged behind North Vietnam’s Tet Offensive, which commenced at the end of January.²⁴ 

Finally, this case illustrates the wartime debate between U.S. military and political leaders over intensifying the conflict. Senior commanders wanted to increase pressure, while civilian leaders steadily refused to expand the war. Even as Hanoi’s politburo approved plans to conduct a general offensive in the south in early 1968, Secretary of Defense Robert S. McNamara and President Lyndon B. Johnson rejected aggressive military options such as Butt Stroke. The fate of the shelved 1967 invasion plans foreshadowed the crumbling U.S. commitment to South Vietnam’s freedom.