Suspected Viet Cong guerrillas are led by U.S. infantrymen to an interrogation point near Saigon during the Vietnam War, Feb. 1, 1966.

When Americans think of Vietnam, they tend to think of a war that put 50,000 American names on the memorial wall in Washington. But the U.S. intervention there also was one of America's most determined nation-building efforts — and perhaps its biggest nation-building failure.

Paradoxically, the United States missed an early chance to exert considerable influence in Vietnam, when Woodrow Wilson spurned a young man who approached him at the Versailles Peace Conference in 1919 and asked for help in gaining Vietnam's independence from the French. That young man instead became a communist and adopted the pseudonym Ho Chi Minh.

After the French defeat in the mid-1950s, Vietnam split into two nations — the communist-controlled North, and a South Vietnamese government headed by Ngo Dinh Diem, who refused to hold national elections. The United States, fearing the spread of communism, backed Diem with military assistance and economic aid, but was unable to strengthen his South Vietnamese state — in large part, because Diem's policies of dismantling village self-rule and promoting his fellow Catholics to government positions alienated the largely Buddhist population.

Diem eventually lost favor with the United States and was overthrown and assassinated in a 1963 military coup. After President Lyndon Johnson drastically escalated the U.S. military presence in Vietnam in 1964, his administration adopted a grass-roots nation-building strategy, dubbed "pacification," in which American soldiers sought to keep communist guerrillas out of villages so that teachers, health-care workers and local government officials could establish themselves.

Another clandestine adjunct was Operation Phoenix, a CIA operation that sought to identify and neutralize communist supporters in villages, often by assassination. But again, ultimately, none of it worked. The United States pulled out of Vietnam in 1973, and two years later the communists seized control of the South.