The quagmire theory comes from David Halberstam's account of the U.S. military policy in Vietnam, The Making of a Quagmire.^[2] Halberstam, a New York Times reporter who was stationed in Vietnam during the war, worked closely with a secret North Vietnamese agent, Phạm Xuân Ẩn. Halberstam left Vietnam in 1964 and won the Pulitzer Prize for international reporting that year. The journalists covering the war in Vietnam were crucial because the only other reporting the American people got was from the government. Halberstam and the other reporters who spent time in Vietnam during the war saw things with their own eyes and were able to recount these events to the American people, changing the view of the war for some.

The theory was more deeply developed by Arthur Schlesinger in his book The Bitter Heritage.^[3] Schlesinger was a U.S. historian who served a special assistant and court historian to President John F. Kennedy. According to the quagmire theory, as described by Schlesinger, the quagmire metaphor represented the one-step-at-a-time process that the U.S. inadvertently became entrapped in the military and diplomatic swamp of Vietnam. Schlesinger detailed the process of American involvement in a war that was not really in the American interest and as a result of inadvertent decision making and false hope.

In retrospect, Vietnam is a triumph of the politics of inadvertence. We have achieved our present entanglement, not after due and deliberate consideration, but through a series of small decisions. It is not only idle but unfair to seek out guilty men. Each step in the deepening of American commitment was reasonably regarded at the time as the last that would be necessary. Yet, in retrospect, each step led only to the next, until we find ourselves entrapped today in that nightmare of American strategists, a land war in Asia--a war which no president... desired or intended.^[4]

Schlesinger believed the war to be a "tragedy without villains" and identified nationalism rather than communism as the most influential factor driving US involvement in Vietnam.^[5] The U.S. estimation of the economic and security risks that Vietnam could cause was exaggerated.^[6] The incorrect assessment of the situation in Vietnam led the U.S. leadership into a series of bad decisions that resulted in the Vietnam War, according to the quagmire theory.

The Vietnam saga started with the colonization of the country by the French in 1887. In 1941, Japan tried to expand its empire by invading Vietnam. The Vietminh, a communist guerilla group, formed in order to successfully drive off the Japanese. After World War II, Harry S. Truman, instituted the foreign policy of containment. First presented in 1946, the goal was to try to contain communism and keep it from spreading around the world.^[7] In the same year, the First Indochina war commenced. This war between the Vietminh and the French concluded with the Battle of Dien Bien Phu, a decisive victory for the Vietminh. Two states emerged from the First Indochina War: the Communist-ruled north and the south, split by the 17th parallel-agreed upon at the Geneva Convention in 1954. Soon after, in 1955, war broke out between the north and south. Domino theory, a well-accepted theory during that time period, introduced by Dwight D. Eisenhower, stated that if one country fell to communism, then the rest of southeast Asia would fall to communism.^[8]

The U.S involvement did not come without warning. French president Charles de Gaulle warned John F. Kennedy that Vietnam was a "a bottomless military and political swamp.".^[9] In 1963, with the approval of the CIA, South Vietnam president Ngo Dinh Diem was overthrown and killed. This sparked a tumultuous period in south Vietnamese politics with many leaders taking over and then quickly losing power. This allowed the north to establish ideological strongholds in the south.

In October 1963, President Kennedy asked the publisher of The New York Times, Arthur Sulzberger, to remove Halberstam from Vietnam.^[10] The White House also suggested that reporters take short trips to Saigon instead of long trips where they could develop their own sources and not rely on government sources for information. However, this suggestion did not have the desired effect, putting more of a spotlight on the issue. The U.S. was accused by reporters in Vietnam of trying to fight too many battles at one time. Was it fighting the Vietcong, communism and the North Vietnamese all at once, all while trying to advise and train the South Vietnamese troops and failing to bring them substantial victories on the battlefield?

In 1964, the Gulf of Tonkin incident sparked the beginning of major U.S involvement.^[11] While off the coast of North Vietnam, the U.S.S Maddox got into a gunfight with three North Vietnamese boats. The Maddox was reported to have fired warning shots at the boats telling them to stay away. The boats then attacked the Maddox, opening up with machine gun fire and sending torpedoes. The Maddox retaliated, hitting all three boats. From this incident came the Gulf of Tonkin Resolution, allowing the U.S. to assist southeast Asian countries fearful of communist aggression. By the next year, U.S troop involvement increased to 200,000. By 1969, the troop level increased up to its height, 549,000.

In 1973 the Paris Peace Accords were agreed to, officially ending U.S involvement in Vietnam. Its final troops left in 1973.

• Driftwood theory