At the end of World War II, the United States was broadly popular in Vietnam for having repelled the Japanese occupiers. Even Ho Chi Minh, the nationalist and communist revolutionary, started off pro-American. But, through the terms of five U.S. presidents, that relationship deteriorated and the United States and Vietnam found themselves at war.

Initially, many Vietnamese appreciated the anti-colonial views of President Franklin D. Roosevelt, who opposed the return of the French colonizers and who asserted in a charter that all people had a right “to choose the form of government under which they will live.” During World War II, Ho Chi Minh received arms from the CIA’s predecessor, helped locate downed American pilots and gathered intelligence on Japanese military positions.

Then, on September 2, 1945, the day of Japan’s official surrender, Ho quoted from the U.S. Declaration of Independence as part of a speech in which he implored the Allies to recognize Vietnam’s independence. He later made multiple additional attempts to get the United States on his side.

The increasing alarm over the spread of communist rule, however, would throw the U.S.-Vietnam relationship off track and eventually into war. Presidents Truman, Eisenhower, Kennedy, Johnson and Nixon oversaw the conflict, which ratcheted up in intensity as the years passed by. Though each president expressed doubts in private about American involvement, none wanted to be blamed for losing Vietnam to the communists.

The war would eventually claim the lives of more than 58,000 Americans and some 3 million Vietnamese.

State Department officials in Asia warned Harry Truman, who became president in 1945 upon Roosevelt’s death, that French rule of Vietnam would lead to “bloodshed and unrest.” But Truman did not share his predecessor’s anti-colonialism and ultimately acquiesced to the reestablishment of France’s prewar empire, which he hoped would shore up France’s economy and national pride.

No sooner did the French arrive back in Vietnam, with the guns of World War II barely gone cold, than fighting broke out against Ho’s Viet Minh forces. At first, the United States remained officially neutral, even as it avoided any contact with Ho. In 1947, however, Truman asserted that U.S. foreign policy was to assist any country whose stability is threatened by communism. Then the outbreak of the Korean War in 1950, plus the flow of aid from China and the Soviet Union to the Viet Minh, prompted Truman to reexamine Vietnam in a Cold War light.

Fearing that Vietnam, too, would become a communist state, he sent over transport planes and jeeps, along with 35 military advisers, as part of a multimillion-dollar aid package.

U.S. involvement in the conflict would only deepen from there. By the end of Truman’s presidency, the United States was funding more than one-third of France’s war costs, a number that would soon skyrocket to about 80 percent.

In 1954, the French suffered a catastrophic defeat at Dien Bien Phu, bringing their colonial reign to an end. Some U.S. officials had pushed for air strikes, including the possible use of nuclear weapons, to save the French position. But Dwight D. Eisenhower, who succeeded Truman, demurred, refusing to involve the United States in another major conflict so soon after the Korean War.

“I am convinced that no military victory is possible in that kind of theater,” the president wrote in his diary.

Yet because Eisenhower subscribed to the “domino theory,” which held that if one country fell to communism then its neighbors would follow, he refused to abandon Vietnam altogether.

The nation was partitioned in two, with Ho in control of the North and pro-Western leader Ngo Dinh Diem in control of the South. Elections were supposed to take place to reunite Vietnam, but Diem, with U.S. support, backed out for fear that Ho would win.

Though Diem proved corrupt and authoritarian, Eisenhower called him “the greatest of statesmen” and “an example for people everywhere who hate tyranny and love freedom.” More importantly, he also supplied Diem with money and weapons, sending nearly $2 billion in aid from 1955 to 1960 and increasing the number of military advisors to around 1,000.

By the time Eisenhower left office, open fighting had broken out between Diem’s forces and the so-called Viet Cong, communist insurgents in the South who were backed by North Vietnam. Each side employed brutal tactics, including torture and political assassinations.

The Vietnam War was now in full swing, and the United States was right in the middle of it.

After visiting Vietnam as a congressman in 1951, John F. Kennedy publicly lambasted U.S. efforts to assist the French, saying that to act “in defiance of innately nationalistic aims spells foredoomed failure.” Three years later, he presciently declared, “I am frankly of the belief that no amount of American military assistance … can conquer an enemy which is everywhere and at the same time nowhere.”

His tune changed, however, by the time he ran for president in 1960, in part over concerns he would be called soft on communism. Once in the White House, Kennedy provided South Vietnam with jet fighters, helicopters, armored personnel carriers, river patrol boats and other tools of war. He also authorized the use of napalm, as well as defoliants such as Agent Orange.

Meanwhile, under his watch, the number of military advisers rose to about 16,000, some of whom began engaging in clandestine combat operations. Originally a supporter of Diem, Kennedy sanctioned a coup in 1963 that resulted in Diem’s death just weeks prior to his own assassination.

Near the end of his life, JFK hinted to aides that he might withdraw from Vietnam following his re-election, but it’s unclear whether he would have actually done so.

At the time of Kennedy’s assassination, U.S. involvement in the Vietnam War remained fairly limited. But that changed in August 1964, when the so-called Gulf of Tonkin incident prompted Congress to grant expansive war-making powers to newly installed President Lyndon B. Johnson.

Recognizing that the South Vietnamese government and army were on the verge of collapse, Johnson sent the first U.S. combat troops into battle in early 1965. He simultaneously authorized a massive bombing campaign, codenamed Operation Rolling Thunder, that would continue unabated for years.

Draft calls soon skyrocketed—along with draft resistance—and by 1967 there were around 500,000 U.S. troops in Vietnam. That same year, large anti-war demonstrations popped up in cities across America.

U.S. officials kept insisting that victory was imminent. But, as the Pentagon Papers would later reveal, these comments were deeply misleading. In reality, the conflict had devolved into a quagmire.

Vietnam became so polarizing, and Johnson’s name became so synonymous with the war effort, that he ultimately decided not to run for re-election in 1968.

Richard Nixon campaigned for the White House promising to end the Vietnam War. It later emerged, however, that he had secretly tried to sabotage peace talks in order to improve his electoral chances.

As president, Nixon gradually withdrew American troops as part of his policy of “Vietnamization.” Yet he escalated the conflict in other ways, approving secret bombing raids of neighboring Cambodia in 1969, sending ground troops into Cambodia in 1970 and sanctioning a similar invasion of Laos in 1971, all in a largely futile attempt to disrupt North Vietnamese supply lines and destroy Viet Cong camps.

Nixon also ordered the most intense air assault of the war, pummeling North Vietnamese cities with roughly 36,000 tons of bombs late in 1972.

In January 1973, just as the Watergate scandal was heating up, Nixon finally ended direct U.S. involvement in Vietnam, saying “peace with honor” had been achieved. As it turned out, though, fighting continued until 1975, when North Vietnamese troops marched into Saigon, South Vietnam’s capital, and reunified the nation under communist rule.