They were supplied with rockets and weapons by China and Russia. They used the Ho Chi Minh Trail - a jungle route through Laos and Cambodia - to supply their armies. The Americans couldn't attack their supply routes without escalating the war.
Their tactic was "hanging onto the belts" of the Americans - staying so close to the Americans so they could not use air or artillery backup without killing their own men.
They forced the peasants to leave Vietcong-controlled areas and made them live in defended strategic hamlets in loyal areas. This created immense opposition, and allowed Vietcong infiltrators into loyal areas.
American troops were sent on patrols, then supported by air and artillery when attacked. This demoralized the soldiers, who realized they were being used just as bait.
Search and destroy patrols went out looking for "Charlie", as they called the Vietcong. But the patrols were very visible, and easy to ambush. This led to atrocities such as "zippo raids" to burn villages, and the unprovoked massacre of peaceful villagers at My Lai in 1968.
- In 1968, the US president, Lyndon B. Johnson, ordered an end to American bombing of North Vietnam.
- There were increasing problems in the American army in Vietnam.
- There was increasing opposition to the war in America.
- Richard Nixon, who became US president in 1969, began Vietnamization - pulling US troops out but giving financial support to the South Vietnamese army (the ARVN).
- On occasions, the US escalated the war, launching attacks into Cambodia (1970) and Laos (1971) to pursue the Vietcong who were hiding there.
- In October 1972 Henry Kissinger worked out a peace agreement with the North Vietnamese.
- Nguyen Van Thieu, the president of South Vietnam, refused to sign (he thought the Americans were going to abandon him), so the North Vietnamese pulled out of the talks.
- Richard Nixon mounted huge bombing raids on North Vietnam until the North Vietnamese were forced to sign.
- Nixon told Thieu he had to make peace whether he agreed with it or not, so Thieu was forced to sign too.
- January 1973: the Paris Peace Agreement was signed, and the Americans left Vietnam.
Why did America lose the war?
Take a look at this table highlighting the differences between the Americans and the Vietcong.
The American hi-tech tactics continually killed the wrong people and demoralized their own troops.
The Vietcong's guerrilla tactics were appropriate to the nature of the conflict.
The US was trying to supply a war 8,000 miles from America.
The Vietcong were supplied with weapons by China and Russia.
The South Vietnamese regime was weak, brutal and corrupt.
The South Vietnamese peasants supported and sheltered the Vietcong.
Their short (one-year) tour of service meant that American troops were always inexperienced.
The Vietcong had been continuously at war since they resisted the Japanese during the Second World War.
The North Vietnamese were motivated, fighting at home to unite their country.
Why did the war arouse so much opposition in America?
58,000 Americans - average age 19 - were killed.
It was hard for Americans to believe that they were defending America by fighting in a war 8,000 miles away.
Extensive media coverage brought all the failures and horrors of the war into US homes.
Atrocities such as the massacre at My Lai undermined the moral authority of the US to continue the war.
The cost of the war meant that the US president Lyndon B. Johnson had to cancel his Great Society program of reform.
The war was opposed particularly by Martin Luther King and by America's black community (because wealthier white men could avoid the draft by going to university or to Canada, and young black men were twice as likely to be killed).