South Vietnamese troops wade through water to flush out communist rebels, known as the Viet Cong, in 1962. Several years earlier, North Vietnamese communists began helping the Viet Cong fight South Vietnamese troops. They wanted to overthrow the South Vietnamese government and reunite the country, which split in 1954.
On July 21, 1954, Vietnam signs the Geneva Accords and divides into two countries at the 17th parallel: the communist-led north and U.S.-supported south. Vietnam had been a part of the colonial empire French Indochina until communists in the north began fighting France for control of the country.
A man appears fearful as he is questioned by South Vietnamese soldiers in August 1962.
American planes drop napalm on Viet Cong positions in 1962. Hoping to stop the spread of communism in Southeast Asia, the U.S. also sent aid and military advisers to help the South Vietnamese government. The number of U.S. military advisers in Vietnam grew from 900 in 1960 to 11,000 in 1962.
U.S. troops in Vietnam salute the coffins of seven American soldiers who were killed in a helicopter crash circa 1963.
Thich Quang Duc, a Buddhist monk, burns himself to death on a street in Saigon -- the capital of South Vietnam -- on June 11, 1963. He lit himself on fire to protest alleged persecution of Buddhists by the South Vietnamese government.
A father holds the body of his child as South Vietnamese Army Rangers look down from their armored vehicle in March 1964. The child was killed as government forces pursued guerrillas into a village near the Cambodian border.
The U.S. Navy destroyer USS Maddox, seen here, was anchored in the Gulf of Tonkin when it was attacked by the North Vietnamese in August 1964. After U.S. President Lyndon Johnson falsely claimed that there had been a second attack on the destroyer, Congress passed the Gulf of Tonkin resolution, which authorized full-scale U.S. intervention in the Vietnam War. Johnson ordered the bombing of North Vietnam in retaliation for the Tonkin attack.
A South Vietnamese reconnaissance unit walks hip-deep in water as a U.S. helicopter skims over reeds in the Mekong Delta in October 1964. They were on the lookout for Viet Cong guerrillas.
Injured people receive medical aid after an explosion at the U.S. Embassy in Saigon on March 30, 1965.
A suspected Viet Cong is kicked by a South Vietnamese soldier in October 1965. The prisoner was one of 15 captured in a raid near Xom Chua.
Women and children crouch in a muddy canal as they take cover from intense Viet Cong fire at Bao Trai, about 20 miles west of Saigon, in January 1966.
Staff Sgt. Harrison Pell, a wounded American soldier, drinks from a comrade's canteen during a January 1966 firefight between U.S. troops and a combined North Vietnamese and Viet Cong force.
A Viet Cong soldier holds an anti-tank gun during the Tet Offensive, a massive surprise attack launched in 1968 by the North Vietnamese. The attack hit 36 major cities and towns in South Vietnam. Both sides suffered heavy casualties.
South Vietnamese Gen. Nguyen Ngoc Loan, chief of the National Police, fires his pistol into the head of suspected Viet Cong officer Nguyen Van Lem on a Saigon street on February 1, 1968, early in the Tet Offensive.
A young refugee carries an elderly woman on his back while crossing a bridge in Hue, Vietnam, in 1968.
Troops look at the aftermath of an attack on the U.S. Embassy in Saigon in 1968.
A U.S. Army first sergeant guides a medevac helicopter through the jungle to pick up casualties suffered near Hue in April 1968.
A South Vietnamese woman mourns over the body of her husband, which was found with 47 others in a mass grave near Hue in April 1969.
U.S. President Richard Nixon points to a map in the White House after telling the nation that American troops have attacked, at his order, a communist complex in Cambodia in April 1970. Nixon ordered troops to invade border areas in Cambodia and destroy supply centers set up by the North Vietnamese.
On May 4, 1970, National Guard units fired into a group of anti-war demonstrators at Kent State University in Ohio. The shots killed four students and wounded nine others. Anti-war demonstrations and riots occurred on hundreds of other campuses throughout May.
U.S. artillerymen relax under a crudely made peace flag at the Laotian border in 1971. In February 1971, U.S. and South Vietnamese troops invaded southern Laos in an effort to stop North Vietnamese supply routes. This action, ordered by President Nixon, was done without consent of Congress, and it led to more anti-war protests.
South Vietnamese forces follow after terrified children after a napalm attack on suspected Viet Cong hiding places in June 1972. A South Vietnamese plane accidentally dropped napalm on South Vietnamese troops and civilians. The terrified girl in the center had ripped off her burning clothes while fleeing.
North Vietnamese Foreign Minister Nouyen Duy Trinm signs a ceasefire agreement in Paris on January 27, 1973. The last American ground troops left in March of that year. Fighting would resume between North and South Vietnam, but the United States did not return.
Air Force Lt. Col. Robert L. Stirm, a released prisoner of war, is greeted by his family in Fairfield, California, as he returns home on March 17, 1973.
A cargo net lifts refugees from a barge so they can be evacuated from the city of Da Nang, Vietnam, on April 1, 1975.
Mobs of Vietnamese people scale the wall of the U.S. Embassy in Saigon on April 29, 1975, trying to get to a helicopter pickup zone. A day later, South Vietnam surrendered to North Vietnam when North Vietnamese troops entered Saigon. Saigon is now called Ho Chi Minh City in honor of the late North Vietnamese leader.
U.S. President Barack Obama stands at the Vietnam Veterans Memorial in Washington in May 2012. The black granite memorial bears the names of more than 58,000 Americans killed in the Vietnam War.