Causes & Effects of the Vietnam War (College Board AP® US History)

Timeline:

1955 – US begins sending financial and military aid to South Vietnam

1964 – Tonkin Gulf Resolution passed; US begins military engagement in Vietnam

1965 – Battle of la Drang Valley

1968 – Tet Offensive

1970 – Cambodia Incursion

March 1973 – Last US troops leave Vietnam

November 1973 – War Powers Act is passed

April 1975 – Vietnam War ends

Summary

As it had done in other countries, the United States entered Vietnam in the early 1960s to stop the spread of communism. The Vietnam War was not like any war that U.S. soldiers and civilians had experienced before. Firstly, the U.S. never officially declared war on communist North Vietnam. Secondly, thanks to television, Americans could see what was happening on the battlefields. They were horrified by the images of bloody warfare and maimed and dead American soldiers broadcast into their homes. 

For the first time, a sizeable portion of the population questioned the United States’ involvement in a global war and the judgement of the presidents who continued to authorize military engagements against the Vietcong. The American people’s faith in government was rapidly declining.

Causes of the Vietnam War

• Nationalist and communist leader Hồ Chi Minh became popular in parts of Vietnam after World War II ended

• Vietnam, Laos, and Cambodia were all formerly a French colony known as Indochina

  • Japan took Indochina during World War II

  • France’s efforts to retake the territories after the war only increased Indigenous people’s support of Hồ Chi Minh and his communist ideas and policies

• An anti-colonial war ensued

  • The result of France’s defeat at Dien Bien Phu was the division of Vietnam at the 17th Parallel until a general election could be held 

    • The election was never held because the South was afraid the Communists would win

  • Hồ Chi Minh was the communist dictator of North Vietnam; Ngô Đình Diệm led South Vietnam

• U.S. President Dwight Eisenhower believed in Domino Theory

  • This stated that, if a non-communist state became communist, it would cause the fall of nearby states to communism, just like a row of dominoes

• Eisenhower used Domino Theory to justify the $1 billion in economic and military aid the U.S. sent to South Vietnam between 1955 and1961

• President John F. Kennedy also believed in this theory 

  • By 1963, he had sent 16,000 “military advisors” to train South Vietnam’s army and fortify their villages 

• In 1964, North Vietnamese gunboats allegedly fired on U.S. warships in the Gulf of Tonkin

• President Lyndon Johnson, who had been accused of “giving weak support” in the fight against the Vietcong guerilla fighters during his presidential campaign, convinced Congress to pass the Gulf of Tonkin Resolution

  • This Act gave the president the power to take “all necessary measures” to protect U.S. interests in Vietnam

    • This meant he could send soldiers into combat even though Congress had not declared war

Major Military Engagements of the Vietnam War

• President Johnson believed that US and South Vietnamese forces could easily overpower the Vietcong and the North Vietnamese Army

  • But the Vietcong were not beaten

• Johnson continually escalated US involvement in the war

  • By the beginning of 1966, 184,000 US troops were in Vietnam

  • By the end of 1967, there were nearly half a million US troops there

Major battles 

• Battle of la Drang Valley (1965)

  • The first major battle between American and Vietcong forces

  • Both sides said they won

• Tet Offensive (1968)

  • The Vietcong made a surprise attack on nearly every major South Vietnamese city and American military base on the Vietnamese Lunar New Year

  • The Vietcong did not have a strategic victory, but videos of the destruction they caused were played on American TV

    • This was a turning point in American opinion against the war

    • Those videos were a political setback for President Johnson’s administration and therefore a political win for the Vietcong

    • Just days after the end of the offensive, Johnson announced he would not run for reelection

• Cambodia Incursion (1970) 

  • President Richard Nixon authorized an incursion, the use of US forces to invade Cambodia and destroy Vietnamese Communist bases hidden in the country

  • Americans were very surprised and upset, because Nixon had campaigned on the promise that he would remove US troops from Vietnam and allow the Vietnamese to settle their own differences

Domestic Effects of the Vietnam War

Debates over the powers of the president

• One of the first controversies regarding the Vietnam War was the Gulf of Tonkin Resolution

• Politicians and citizens debated the legality of giving the president unilateral war powers in a situation where Congress did not officially declare war, as required by the Constitution

  • Technically, the executive branch already had congressional approval for military intervention in Vietnam 

  • It had been given to President Kennedy for sending “military advisors” into the country

    • However, Johnson had not been given approval for military engagement

• One result was the War Powers Act (1973)

  • The War Powers Act required the president to:

    • report to Congress within 48 hours of taking military action

    • receive congressional approval for any military action lasting more than 60 days

  • The War Powers Act was also a response to the Cambodia Incursion and other instances of presidents authorizing secret military actions in Southeast Asia

Television and the Vietnam War

• The Vietnam War was the first televised war

• People could see for themselves what was happening on the battlefield, and it did not match what the politicians were saying

  • This caused a credibility gap, which made people distrust the government

• Americans split into two camps: those who supported the war, called Hawks, and those who opposed the war, called Doves

  • Hawks thought the war was part of a Soviet master plan to conquer Southeast Asia

    • They thought it was the United States’ duty to stop the spread of communism

  • Doves viewed the war as a civil war in which the United States did not need to take part, even if communism was a factor

• This was the first American war with an associated protest culture

  • Many people opposed the war because of the number of lives lost and how much money it cost

    • They argued that all that money could be spent on problems facing the US

    • The largest demographic group protesting the war was college students, many of whom would be drafted into military service upon graduation