Despite having no aircraft, tanks or artillery of their own, the Vietcong managed to hold out against the Americans until the USA left Vietnam in the 1970s. The Vietcong used a number of tactics to help them do this.
Guerrilla warfare is the art of using knowledge of the landscape to avoid open battle with the enemy and to launch raids and surprise attacks, before disappearing back into the undergrowth.
The Vietcong had experience of doing this while fighting the Japanese and the French after World War Two - they were very familiar with the terrain and the climate. They used the Ho Chi Minh Trail, which stretched from North Vietnam to the South, to keep their forces supplied.
The Vietcong won the ‘hearts and minds’ of the South Vietnamese peasants. They would offer to help them in their daily work and also promised them land, more wealth and freedom under Ho Chi Minh and the communists.
It was difficult for American troops to know who was a Vietcong and who was not.
The Vietcong had a hidden system of tunnels stretching over 200 miles. There were hospitals, armouries, sleeping quarters, kitchens and wells underground. These tunnel systems could hide thousands of Vietcong which helped them fight their guerrilla war.
It would be the job of US ‘tunnel rats’ to search these tunnels. However, they were often booby-trapped with spikes and grenades.
The Vietcong and North Vietnam were supported by the Soviet Union (USSR) and China who supplied money and weapons.
On January 31 1968, the Vietcong changed tactics from their usual guerilla warfare strategy. During celebrations of the Vietnamese New Year (known as Tet) North Vietnam, supported by South Vietnamese Vietcong launched a number of surprise assaults on towns and cities in US-held areas of South Vietnam. They took control of parts of Saigon and other cities, having most success in Vietnam's ancient capital, Hue. One group managed to blow a hole in the walls around the US Embassy in Saigon.
The Vietcong did not hold onto any of the territory gained for long. They suffered many casualites and the Tet Offensive was a military defeat for them.
The offensive failed but has been viewed as a turning point. It had two important effects: