Lucien Conein was born in Paris and grew up in the United States when his mother sent him to live with her sister, who had married a World War 1 veteran. In 1940, Conein volunteered for the French Army, and when France surrendered in late June 1940, he deserted and, after some obstacles, made his way to America. The newly formed OSS (Office of Strategic Services), forerunner of the Central Intelligence Agency (CIA), recruited him, and he parachuted into France to work for the resistance. When the war in Europe ended, he joined a commando group harassing the Japanese in northern Vietnam. Conein entered Hanoi when Japan surrendered and met with Ho Chi Minh and other Vietminh leaders. Between 1954 and 1956, Conein was back in Vietnam as part of Edward Lansdale's intelligence mission.
In 1962, Conein was reassigned to Vietnam as an army lieutenant colonel assigned to the Interior Ministry, but his actual job was to maintain CIA contacts with Vietnamese generals. Nearly all of them trusted Conein. Several of them trusted only Conein, because he once had been their commanding officer in the 1940s and early 1950s. Conein's codename in 1962 and 1963 was Lulu or Black Luigi. His chief role in Vietnam at that time was in the military coup against Ngo Dinh Diem in 1963. Conein knew that American support for Diem had all but vanished, and he worked with the generals to let them know that the United States would look favorably on a change in government. The coup, as well as Diem's assassination, took place on November 1, 1963. Conein departed Vietnam soon after that and retired from government service early in the 1970s.