The Hunt for the Elusive COSVN: Operation Junction City

War Zone C was a roughly triangular region flush with the Cambodian border, pointing at Saigon from the northwest. The area was a common infiltration point for North Vietnamese forces and materiel entering South Vietnam from the Ho Chi Minh Trail. On the 22nd day of February 1967, the U.S. Army opened up the largest offensive in Vietnam to-date, driving through swamps and jungles of War Zone C in search for COSVN, the secret headquarters of enemy military operations in South Vietnam.

Under the control of II Field Forces, Vietnam, about 35,000 men were deployed in the field during various stages of the operation, code-named Junction City. It included the largest parachute landing of the Vietnam War and involved the largest single-day helicopter troop transport operation in the history of Army Aviation.

The Central Office for South Vietnam

The Central Office for South Vietnam, or COSVN, consisted of two parallel organizations set up by the Central Committee of the Labor Party of Vietnam, the precursor of the Communist Party of Vietnam. Their mission was to direct the struggle in South Vietnam against the American-backed government in Saigon. No COSVN permanent physical infrastructure was ever discovered or claimed by first-hand sources to have existed. This "Pentagon in the jungle" was constantly on the move, in order to avoid being wiped out.

In early 1967, COSVN was thought to be in War Zone C, and was even believed by some to be housed in a permanent physical headquarters complete with full-time office staff. Additionally, War Zone C was the normal operating area for the 9th Viet Cong Division, one of the enemy’s best formations.

War Zone C Map
War Zone C is outlined in this map of South Vietnam's III Corps Tactical Zone. The source is "Cedar Falls - Junction City: A Turning Point", Department of the Army, 1989.

Search and Destroy in Vietnam

1966 was the year of accelerated build-up of U.S. forces in Vietnam and marked the beginning of major offensive operations. By 1967, General William C. Westmoreland, Commander of U.S. Military Assistance Command, Vietnam (MACV), had set the focus of combat operations on finding and destroying Viet Cong and People's Army of Vietnam forces in a war of attrition. Official policy constraints denied Westmoreland the authority to strike enemy sanctuaries and supply routes in Cambodia, Laos, and North Vietnam. The general determined that victory could only be achieved by making the war so costly for Hanoi that it would feel compelled to abandon efforts to force the reunification of Vietnam.

Accordingly, the following division of labor between South Vietnamese and American forces was established: The Army of the Republic of Vietnam (ARVN) focused on protecting and pacifying major population centers, while U.S. forces sought to engage the enemy in search and destroy operations conducted in the sparsely inhabited border region near Cambodia and Laos. These violent assaults by infantry and armored units capitalized on rapid helicopter transportation. With heavy supporting firepower, search and destroy operations sought to locate, fix and eradicate enemy troop concentrations and their base areas.

Operation Junction City

While the central aim of Operation Junction City was to eliminate COSVN, its larger mission was far more ambitious and encompassing. The plan called for a massive two and one-half month sweep of War Zone C, aimed at crippling the 9th Viet Cong Division and opening up the area for further clearing operations. The long-range objective was to permanently deny use of the area as a sanctuary for Communist forces, so that pacification efforts could proceed there.

Junction City was devised as a two-phased operation employing a variation on the "hammer and anvil" tactic used in Operation Cedar Falls, on a much larger scale. The plan called for five American brigades to take blocking positions in the western half of War Zone C, forming a giant, inverted horseshoe-shaped cordon. Once the blocking forces were in place, the 11th Armored Cavalry Regiment and the 2nd Brigade, 25th Infantry Division would sweep south-to-north, into the giant inverted horseshoe. This movement would drive the Viet Cong into the U.S. blocking positions, where they could be destroyed.

Video clips released by the 11th Armored Cavalry Regiment, showing troops and armored vehicles in Operation Junction City. The tank shown at the beginning was an M48 Patton, which saw extensive action in Vietnam.

Historian and Vietnam War veteran James H. Willbanks explains in Vietnam: The Course of a Conflict that 249 helicopters were needed to move eight infantry battalions into their blocking positions, requiring the 173rd Airborne Brigade to move three battalions into their assigned blocking positions via parachute jump. It was hoped that timely deployments and tightly controlled movements would prevent COSVN and the 9th Viet Cong Division from evacuating the area. Fire support for the infantry would be provided by 17 artillery battalions and over 4,000 close air support sorties. Airspace control and coordination above the arena was obviously a major concern.

The Profound Disappointment of Search and Destroy

Operation Junction City failed to yield any long-term strategic advantage. The enemy was able to escape across the border into their Cambodian sanctuaries. The opening assaults on the periphery of the horseshoe achieved tactical surprise, but the shape and purpose of the cordon quickly became clear to the enemy and they immediately dispersed. There were some sharp battles on the periphery of the horseshoe, where allied forces were able to destroy some Viet Cong formations, although the preponderance of enemy forces, including the ever elusive COSVN headquarters, escaped to fight another day.

War Zone C remained far from neutralized. Three enemy regiments were shattered in the fighting, but they would be back in force in less than a year later. As it had been shown that the major Viet Cong operating and supply bases in South Vietnam were vulnerable to superior U.S. firepower and mobility, COSVN headquarters were permanently relocated across the border in Cambodian territory. With the White House unwilling to send American combat forces across the border, U.S. commanders were left with little choice but to pursue a defensive strategy of wearing down the People's Army of Vietnam and their Viet Cong militia forces through attrition.

Enemy strongholds in the region between Saigon and Cambodia were repeatedly fought over until the fall of Saigon in 1975. Impressive search and destroy operations like Junction City achieved no lasting strategic benefit. The result was a bloody stalemate with mounting casualties on both sides.