By September 1966, there were 385,000 US troops in Vietnam and the most recently arrived were the 4500 of the 196th Light Infantry Brigade from Ft Devens, Massachusetts. By mid-October, their base camps were built in the operationally important Tay Ninh Province, the gateway to Saigon from the Cambodian border. On 25 September 1966, the arctic trained Brigade began Operation Attleboro, a series of battalion search and destroy missions into the sparsely populated countryside, as more of a training exercise to confirm standard operating procedures and familiarize themselves with air mobile operations in Vietnam.
Surprisingly, Operation Attleboro was initially spectacularly successful beyond the wildest fever dreams of its commander. The sweeps just south of the expansive Michelin Rubber Plantation had little contact and uncovered massive supply caches: one cache located by the “Polar Bears” of 4-31 IN had 843 tons of rice, enough to feed thousands of VC for months. The Americans had inadvertently stumbled on the prepositioned supplies of the entire 9th VC Division and the elite 101st Brigade of the North Vietnamese Army.
Both communist units were just across the border in Cambodia in a base area known to the Americans as the “Fishhook”, where they were conducting their final training and preparation for their assault on the newly arrived 196th. Gen Giap in Hanoi had personally selected the 196th for destruction in order to inflame the burgeoning US anti-war movement. And instead of having to assault their base camps, the brigade had come into the open. As the 196th painstakingly cleared the caches and redistributed the rice, the Communists moved to assault positions.
Among the mounds of weapons, ammunition, and medical supplies, the 196th found documents detailing another large logistics complex (the NVA brigade’s prepositioned supplies) along the Suoi Bao stream off the Saigon River, about 6 km away. The 196th’s commander, feeling pretty cocky, developed an overly complicated plan to assault the area from all four directions, with none of his battalions in mutual support. Despite protests from the battalion commanders, who were all infantrymen, that command and control would be impossible in the dense terrain, the brigade commander, an artilleryman in World War II, ordered the operation forward assuming the same level of opposition as before. He could not have been more wrong.
On 3 November 1966, the brigade air assaulted into widely scattered landing zones around the logistics complex and were immediately swarmed upon by the entire 9th VC Division and its supporting North Vietnamese regulars. For three days (about as long as a human can stay awake and coherently fight), 4000 Americans and 9000 Communists locked horns in a small 14 square km area of jungle and swamp, where as predicted, command and control broke down at the tactical level. Both sides fought each other to exhaustion. Every American company had at least 40% casualties and when they trudged to their landing zones for extraction on 6 November, the men of the 196th assumed they had gotten their asses kicked. They were also wrong.
The Vietnamese had gotten as good as they gave, but what they hadn’t counted on was the ability of the Americans to mass forces quickly. At the ardent behest of the nearby 1st Infantry Division’s commander, MG William DePuy, the Americans air assaulted nearby battalions in to continue the fight. For the next three weeks, a new brigade from either the 1st ID or 4th ID, and the 173rd were inserted into Tay Ninh Provice to continue the destruction of the Communist units. At first Giap tried to do the same by marching in from Cambodia, but soon realized he was just feeding good men into a battle he could not win against superior American mobility and firepower. The 9th VC Division and its NVA attachment were destroyed, the logistics areas cleared, and the Tay Ninh Province quiet for the next year in America’s first corps level operation of the Vietnam War.
But Giap took advantage of the quiet area and forbade future contact there, if possible. As American units moved on to other “hot” areas, such as “The Iron Triangle” further south, Giap’s Central Office of South Vietnam (COSVN), the primary Communist headquarters outside of Hanoi, established itself just across the Cambodian border in the Fishhook. COSVN used the “pacified” but now nearly unpopulated Tay Ninh province as a transit point to infiltrate men, supplies and equipment from the Ho Chi Minh Trail to VC and NVA units in the south. The province was simply too large and too sparsely populated for the South Vietnamese CIDG battalions to control or even know what was going on in the area. Americans would occasionally sweep the area (Operation Junction City in 1967) but never stayed. Most of the supplies used in the south during the Tet Offensive 14 mos later came thru Tay Ninh. This would continue until Nixon’s invasion of Cambodia in 1970, whose primary objective was the Fishhook.