Probably on the very first patrol anyone went on. The Vietcong tunneled pretty constantly throughout the war.
If you mean who the enemy was, it were the: North Vietnamese Army Vietcong Khmer Rouge and the Pathet Lao While the "Main Enemies" Were the vietcong and the north vietnamese army.
The VC (Vietcong) and NVA (North Vietnamese Army).
Communist guerrilla movement in Vietnam that fought the South Vietnamese government forces 1954-75 with the support of the North Vietnamese army and opposed the South Vietnamese and US forces in the Vietnam War.
The local VC took their orders from Hanoi. The NVA was Hanoi's regular army.
The Viet Cong were a cadre of patriot civilians in South Vietnam who were willing to fight for Vietnam's unification. The North Vietnamese Army was assembled and trained in the North, and sent south to fight to discourage and remove the United States and their allies from what they called the 'occupation' of South Vietnam.
As the fighting intensified between the Vietcong and the South Vietnamese army, President Eisenhower sought to support South Vietnam by providing military aid and financial assistance. He also increased the number of military advisors in the region, sending over 600 U.S. personnel to assist the South Vietnamese forces. Eisenhower's administration aimed to bolster the South Vietnamese government in its fight against communism, reflecting the broader U.S. policy of containment during the Cold War.
The Vietcong and the North Vietnamese Army (NVA) offset their inferior firepower by employing guerrilla tactics, utilizing knowledge of the local terrain to conduct ambushes and hit-and-run attacks. They also relied heavily on a network of tunnels for surprise assaults and to evade enemy forces. Additionally, they garnered support from the local population, which provided resources and intelligence, and they effectively used propaganda to maintain morale and enlist support for their cause.
The Vietcong were a light infantry force, primarily used for guerrilla warfare. They had virtually no heavy equipment and no navy or air force. Like most guerrilla forces, they had virtually no training in infantry tactics, and poor leadership. They were used by the main North Vietnamese Army to harass the ARVN and US forces, and to conduct politically-oriented actions against South Vietnamese citizens. The Vietcong's primary value was to provide the illusion of a threat to the ARVN and US forces, and to be a large political lever to use against the South Vietnamese government.
It isn't known. Vietnam in 1995 estimated total North Vietnamese army and southern NLF deaths combined at 1.1 million, most of them thought to be army rather than irregulars.
The Tet Offensive was the largest blow to the Johnson's Vietnam "Police policy". The Vietcong along with the North Vietnamese Communist Army laid low for a while. Just as Generals thought they had eliminated all of the Vietcong in South Vietnam. The Vietcong and the N. Vietnamese army launched a large offensive on several key cities including Saigon. Although in a weeks time the American troops were able to re-claim all of the recently captured cities. The Tet Offensive largest blow had been a political one. The offensive proved that the Vietcong were still a very prevalent threat in South Vietnam
The Vietcong was a political organization and army in South Vietnam and Cambodia that fought the United States and South Vietnamese governments during the Vietnam War (1955-1975).
Ho Chi Minh said, "Defend the North, Free the South, and Unite the Country." The North rallied around defeating foreign invaders and their corrupt puppets.