35 years after the fall: The Vietnam War in pictures

U.S. military action in Vietnam was a piece in the global Cold War struggle. After Vietnamese nationalists overthrew French colonialists in the 1950s, the country was divided between the Communist north and the anti-Communist south. In the ensuing conflict, Washington backed the south, fearing that a Communist takeover could cascade through Southeast Asia. The first U.S. forces engaged in the conflict in secret, by way of Cambodia. As the civil war intensified in the 1960s, the United States expanded its operations in the region, deploying some 3 million American troops over time, but U.S. forces struggled to gain ground as they fought in difficult and unfamiliar terrain against extremely capable in guerrilla fighters. As the war dragged on and casualties mounted, opposition to the war exploded. By the time American forces withdrew in 1975 and Saigon fell to Ho Chi Minh's Communists, 58,000 Americans and between 1 million and 2 million Vietnamese had died. It was the longest war in U.S. history and the most unpopular American war of the 20th century. In this 1965 photo, paratroopers cross a river in the rain near Ben Cat, in the south.

The South Vietnamese regime backed by the United States in the early days of the conflict was notoriously corrupt and authoritarian. President Ngo Dinh Diem, who was part of the Catholic minority, populated his government and military with Catholics, fomenting widespread unrest among the country's Buddhist majority. In this image taken June 11, 1963, Buddhist monk Quang Duc burns himself to death at a busy Saigon intersection to protest persecution of Buddhists. The picture came to represent the failure of the Diem regime and a growing public relations problem for the U.S. Several months later, Diem was overthrown, executed and buried in an unmarked grave.

Hovering U.S. Army helicopters pour machine gun fire into a tree line to cover the advance of South Vietnamese ground troops in March 1965. The troops were moving to attack a Viet Cong camp northwest of Saigon near the Cambodian border.

A Vietnamese man holds the body of his child as South Vietnamese Army Rangers look down from their armored vehicle near the Cambodian border on March 19, 1964.

An unidentified U.S. Army soldier sports the slogan "War Is Hell" on his helmet in Vietnam on June 18, 1965.

A South Vietnamese soldier beats a farmer with the blunt end of a knife for allegedly supplying inaccurate information about the movement of Viet Cong guerrillas in a village west of Saigon. Jan. 9, 1964.

Comedian and actor Bob Hope entertains U.S. troops in front of the Hotel Hispanola, which was used as officers' quarters in Santo Domingo, Dominican Republic, during the Vietnam War in 1965. Hope did regular tours abroad as a salute to American troops from 1964 through 1972, a tradition he had established during World War II.

U.S. Marines emerge from their muddy foxholes at sunrise after a third night of attacks by North Vietnamese troops on Sept. 21, 1966.

The body of an American paratrooper killed in action near the Cambodian border is raised to an evacuation helicopter in Vietnam in 1966. More than 58,000 Americans were killed and 350,000 wounded in the war.

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 on Jan. 1, 1966.

Wounded Marine Gunnery Sgt. Jeremiah Purdie is led past stricken comrades after a fierce firefight for control of Hill 484 south of Vietnam's demilitarized zone in 1966.

U.S. Army helicopters providing support for ground troops fly into a staging area 50 miles northeast of Saigon in South Vietnam in 1966.

U.S. Army medic James E. Callahan of Pittsfield, Mass., tends to a seriously wounded soldier north of Saigon in June 1967.

American infantrymen crowd into a mud-filled bomb crater and look up at tall jungle trees seeking out Viet Cong snipers firing at them during a battle in Phuoc Vinh, north-northeast of Saigon on June 15, 1967.

A soldier of the U.S. Seventh Marines carries a puppy in his pocket after rescuing it during an operation southwest of Da Nang in Vietnam on Jan. 22, 1968.

A South Vietnamese woman mourns over the body of her husband, found with 47 others in a mass grave near Hue in April 1969.

South Vietnamese Gen. Nguyen Ngoc Loan, chief of the national police, shoots suspected Viet Cong officer Nguyen Van Lem, also known as Bay Lop, on a Saigon street on Feb. 1, 1968.

In his first year in office, President Richard Nixon speaks with U.S. soldiers during a surprise visit to South Vietnam on July 30, 1969. After coming to office that January, Nixon escalated the war. But he later negotiated a ceasefire with North Vietnam that led to the American withdrawal.

Veterans of the Vietnam conflict take part in an anti-war protest by piling their medals, decorations and awards in front of the U.S. Capitol on April 26, 1971. A veteran adds his helmet to the pile.

Nine-year-old Kim Phuc, center, runs down Route 1 near Trang Bang, Vietnam, after an aerial napalm attack on June 8, 1972.

Lt. Col. Robert L. Stirm is greeted by his family at Travis Air Force Base in Fairfield, Calif., on March 17, 1973, after returning home from Vietnam, where he had spent five years as a prisoner of war. The image came to symbolize the end of U.S. involvement in the war. The family from Stirm's right, are Lorrie Stirm, Bo Stirm, Cindy Stirm, Loretta Stirm and Roger Stirm.

U.S. Navy personnel aboard the USS Blue Ridge push a helicopter into the sea off the coast of Vietnam in order to make room for more evacuation flights from Saigon on April 29, 1975.

A South Vietnamese mother and her three children on the deck of an amphibious command ship being after being airlifted out of Saigon by U.S. Marine helicopters on April 29, 1975.

A North Vietnamese tank rolls through the gate of the Presidential Palace in Saigon, marking the fall of South Vietnam to Communist forces on April 30, 1975. Saigon was rennamed Ho Chi Minh City, and the country was unified under Communist rule.