Although the devastating battles in 1966 and early 1967 killed nearly 100,000 North Vietnamese and Viet Cong, it wasn’t enough. Analysis of population estimates of North Vietnam found that 200,000 North Vietnamese reached draftable age every year. “Body Count” wasn’t going to work, and Gen. Westmoreland, the commander of the American Military Assistance Command – Vietnam, knew it.

The alternative was to cut the Ho Chi Minh Trail at its junctions in Laos and Cambodia, thereby preventing the North Vietnamese Army from replacing the losses suffered by the Main Force units and the Viet Cong in South Vietnam. In the early spring of 1967, Westmoreland’s planners devised Operation York, the simultaneous assault on the Laotian Panhandle opposite Khe Sahn and Hue near the DMZ, and the “Fishhook” in Cambodia. These attacks would have severed the Ho Chi Minh Trail, and “was our worst fear” according to Col. Bui Tuin, a senior North Vietnamese member of Giap’s staff. Westmoreland requested 200,000 more troops to conduct Operation York.

The air war was routinely working over the eastern portions of Laos and Cambodia, but to little effect. The expansion of the ground war into both countries would come at a significant political cost at home. And President Johnson was unwilling to pay it. Secretary of Defense Robert McNamara told Westmoreland to find a “Plan B”. The decision effectively made the war militarily unwinnable for America and its allies, unless the North Vietnamese did something rash (like launch themselves into the teeth of American firepower and be slaughtered… *cough* Tet *cough*).

Westmoreland’s “Plan B” was to block the major Ho Chi Minh Trail outlets into South Vietnam. He couldn’t defend the entire border with the available troops, so his only alternative was to prevent infiltration in several key areas. To this end, Johnson approved an increase in total American personnel in Vietnam by 47,000 (to 536,100, the highest it would go in war). Westmoreland ordered his commanders to seal the major infiltration routes into South Vietnam at or near the border, and leave securing the population in the interior to the South Vietnamese. In the south in the III Corps sector, this was already being done in War Zones C and D by the 1st and 25th Infantry Divisions opposite the Fishhook, and they continued for the rest of 1967.

II Corps was the main effort, with a series of continuous operations in the Central Highlands and the Coastal Plains to secure Central Vietnam. Along the coast was a massive clearing operation, Operation Pershing, in the Binh Long province by the 1st Cavalry Division. In the Central Highlands, the 4th Infantry Division embarked on Operation Francis Marion to establish a mobile defense in depth based on a series of hills, near Dak To, along the border where Laos, Cambodia, and South Vietnam met.

In the north along the DMZ opposite the middle Laotian Panhandle, the Marines would continue the series of successful Lam Son, Prairie, and Hickory operations with the ARVN (I mean, as successful as you can be when the enemy can just scoot back across the border after being defeated). However, until the remaining troops Johnson approved arrived in country, which would take some months, Giap’s superhighway into South Vietnam, the A Shau Valley in I Corps sector, would be left to the ARVN, CIDG, and Special Forces around Hue, with supporting airpower. The city with its massive citadel is located at the narrowest portion of Vietnam. (“The ancient city of Hue” was established in the mid-17th Century, which makes it “about as ancient as Philadelphia”).

At the time, the population of Hue, like all urban areas in South Vietnam, was mostly in support of the Thieu regime, though not completely. Westmoreland’s planners surmised that if there was an area that allowed for an economy of force, it was around Hue. In any case, the A Shau Valley was the largest Communist sanctuary in South Vietnam and couldn’t be cleared without a massive expenditure of resources. The A Shau would have to wait until II and III Corps were finished further to the south.

For the rest of 1967, Westmoreland sent the Americans to the border, while the ARVN and CIDG, stiffened by the Korean divisions and the Special Forces, held the interior. Though he had no choice, Westmoreland inadvertently played directly into the North Vietnamese hands.

Into North Vietnamese hands, but not Giap’s. An internal power struggle raged inside North Vietnam between those who wanted to return to guerrilla operations in the south, (to offset the massive casualties of 66 and 67) led by Giap and Ho, and those that wanted continue main force operations (which was how they defeated the French) led by the COSVN commander Nguyen Chi Thanh, and Le Duan, the General Secretary of the Vietnamese Communist Party. In the eyes of Giap, Thanh was thoroughly discredited by his failure to destroy any significant American force with his costly assaults on the Junction City troops. In May 1967, Thanh returned north to plead his case for continued main force operations, but suddenly died “of a heart attack” in June. Giap won, or so he thought.

Unfortunately for Giap and a few hundred thousand North Vietnamese and Viet Cong, the last thing Thanh did before his “heart attack”, was brief the North Vietnamese politburo on a plan to defeat South Vietnam in early 1968. The plan had six key elements: First, North Vietnamese units would infiltrate South Vietnam in large numbers to replace Viet Cong casualties. Second, the NVA would begin a series of large scale border operations to bring American forces away from the population centers, which the Americans had obliging agreed to do. Thirdly, the NVA would make every effort to overrun the remote US Marine outpost at Khe Sanh along the Laotian border. The hope was for a repeat of their victory at Dien Ben Phu, which decisively swayed world opinion against the French a decade before. Next, as part of a comprehensive information operations campaign against the South Vietnamese government, the Viet Cong would begin a massive campaign of terrorist bombings in the cities to weary the population. As the final point of the preparation the North Vietnamese would return to negotiations to stop the disruptive bombing of the Trail (which surprisingly for North Vietnam, Johnson agreed to as a condition just for the North to return to the table). Finally, after all was prepared, Communist forces would attack every major South Vietnamese, American, and Allied government and military facility during the annual Tet cease fire in late January 1968. By Thanh’s reasoning, this would spark a massive uprising among the South Vietnamese civilian population and disintegrate the South Vietnamese government and army. With the American troops at the border, their airbases overrun, and the North in control of the population, Johnson would have no choice but to withdraw American and Allied troops from Vietnam immediately. The Politburo approved Thanh’s plan, known as “Tong-Tan-cong-Noi-day”, “The General Offensive – The General Uprising”, and ordered Giap to execute it.

Giap was powerless to refuse. Thanh was replaced by his competent subordinate Tran Van Tra, who proved to be a worthy political adversary for Giap, and effectively neutered any support Giap had inside COSVN. More importantly though, by 1967, Ho Chi Minh was deathly ill, and spent most of his time in a hospital in China (Ho would die in 1968). Without Ho’s influence in the politburo, Giap could not refuse Le Duan, especially since most of Ho’s faction was “purged” (read: assassinated) in June and July.

Giap could not prevent what he was sure would lead to the destruction of the Viet Cong and the needless slaughter of the North Vietnamese Army (He was right). Giap reluctantly agreed to The General Offensive, The General Uprising. However, despite the predicted heavy losses, the Tet Offensive was win-win for pragmatic Giap: If it worked, the plan would end the war and unite Vietnam; if it failed, he could place blame and take advantage of the situation politically. Moreover, the losses would inflame the American anti-war movement.

For the remainder of 1967, Giap fed troops into the Central Highlands into what the Americans were increasingly calling the Battle of Dak To, while laying siege to Khe Sanh in the north. All along the South Vietnamese border with Laos and Cambodia, Americans were drawn into battle with increasingly aggressive NVA attacks. Guerilla attacks on military targets in the interior dropped and bombings of civilian targets in the cities dramatically increased. But the border attacks and the Communist actions in the interior were just ruses: in the last six months of 1967, Giap infiltrated nearly 100,000 new NVA soldiers into South Vietnam. The centerpieces for the Tet Offensive would be the capture of its great cities: Hue, Da Nang, Nha Trang, and Saigon. At the end of the A Shau Valley outside Hue alone, 15,000 NVA soldiers waited patiently, while the VC prepped the battlefield. There were even more outside Saigon. Every South Vietnamese government facility, and every official and senior army officer’s home and family were targeted.

Westmoreland assumed his plan to stop the men and supplies coming down the Ho Chi Minh Trail at the border was working, and briefed Johnson and McNamara that he “could see the light at the end of the tunnel”.

He was wrong, but so were La Duan and Tra – Both sides would pay a terrible price in 1968 for their miscalculations.