North Vietnamese Army Officer Bui Tin, second from right, shakes hands with a sergeant in the Air Force as the last U.S. combat troops depart from Vietnam in 1973. (Bettmann Archive/Getty Images)

When the first communist tank charged through the gates of the Independence Palace in Saigon, it fell to Bui Tin, a journalist in the North Vietnamese army, to break the news: The revolution had arrived. Although it had taken the tanks longer than expected (the unit had to stop and ask for directions to the palace), the Vietnam War had come to an end.

Tin was a reporter, not a soldier, but he was still a colonel, the highest-ranking officer on the scene. For reasons of authority and seniority, the commander of the tank unit insisted he, and no one else, accept the surrender of the last president of South Vietnam.

And so it was Col. Tin who strolled into the palace’s second-floor salon a few minutes after 11 a.m. on April 30, 1975, where the country’s president — a 200-pound general named Duong Van “Big” Minh — told him he had been waiting “since morning to transfer power.”

“There is no question of your transferring power,” Col. Tin said, according to journalist A.J. Langguth’s book “Our Vietnam.” “Your power has crumbled. You cannot give up what you do not have.”

“You have nothing to fear,” he added, as gunfire sounded outside. “Between Vietnamese, there are no victors and no vanquished. Only the Americans have been beaten. If you are patriots, consider this a moment of joy. The war for our country is over.”

For Col. Tin, the charismatic son of a government minister, the episode marked the culmination of three decades of wartime sacrifice and unusual good fortune. Striding onto the historical stage at pivotal moments — the battle of Dien Bien Phu, the creation of the Ho Chi Minh Trail, the 1978 invasion of Cambodia — he eventually became a leading opponent of the state he helped build, settling in France to broadcast an anti-communist “petition” that reportedly reached 3 million Vietnamese.

Col. Tin in 2000. (Jacques Demarthon/AFP via Getty Images)

He died Aug. 11, at 90, at a hospital near his home in the Paris suburbs. He had received kidney dialysis and recently fallen into a coma, said his friend Tuong An, a Vietnamese journalist.

Although his family had helped administer the country during French colonial rule, Col. Tin and his father were early backers of the nationalist Viet Minh movement led by Ho Chi Minh, whom the son went on to protect as a member of the communist leader’s personal guard.

Born in the northern city of Nam Dinh on Dec. 29, 1927, he joined the Communist Party at 19. In a memoir, “Following Ho Chi Minh” (1995), he recalled that he “swore an oath under the light of an oil lamp always to be loyal to the idea of liberating the people and the whole of mankind. . . . I equated joining the Party with patriotism and gaining independence. A life full of activity, yet simple, beckoned; it would be bright and glorious without a ripple of concern dis­cern­ible in the future.”

Less than a decade later, Col. Tin was wounded during a French airstrike at Dien Bien Phu. The battle resulted in a 1954 cease-fire that gave Vietnam its independence from France and split the country in two, setting the stage for a 20-year conflict with the American-backed South Vietnamese government.

Col. Tin said he helped plan the deployment of northern troops into South Vietnam in the early 1960s, when he ventured down the Ho Chi Minh Trail in the years before it was widened into a jungle superhighway for communist troops and supplies.

But he found that he was more suited to communications than combat, and he worked as a reporter and military spokesman amid negotiations over prisoners of war and a cease-fire agreement. In March 1973, when the last U.S. combat troops boarded a plane and departed Vietnam, Col. Tin was there on the Saigon airstrip to bid them farewell.

“This is an historic day,” he told The Washington Post, after handing one of the last remaining U.S. soldiers a goodbye package that included Ho Chi Minh postcards and a bamboo scroll painting. “It is the first time in 100 years that there are no foreign troops on the soil of Vietnam.”

Col. Tin went on to serve as deputy editor in chief at both Quan Doi Nhan Dan, the army newspaper, and Nhan Dan, the Vietnamese Pravda. The latter effectively made him a deputy minister, said political scientist Tuong Vu, author of “Vietnam’s Communist Revolution,” although Col. Tin was unable to convince the country’s political leaders of his more liberal ideas on how to rebuild a unified Vietnam.

As he had in Saigon, he accompanied Vietnamese tanks during the invasion of Phnom Penh, which followed Cambodian incursions into Vietnam. But he failed to convince the country’s military and political leaders to quickly end the war, arguing that Cambodia’s fate should be left to the international community.

So, too, was he unsuccessful in advising against collectivization programs in South Vietnam and against “reeducation” efforts that forced an estimated 300,000 South Vietnamese officials, soldiers and supporters into prison camps.

By 1990, he had become fed up with the country’s politics. When the French communist newspaper L’Humanité invited him to Paris, he bought a plane ticket and embarked on a new life as a dissident, delivering what he called “a petition from a single, ordinary citizen” — a multipart, pro-democracy radio broadcast on the BBC’s Vietnamese-language service.

“Bureaucracy, irresponsibility, egoism, corruption and fraud are becoming entrenched under an insolent reign of privileges and prerogatives,” he said in one broadcast. In a subsequent column for The Washington Post, he wrote: “The tragic irony of this situation is that the Communists have finished what America’s military machine only partly did during the war. They have crushed Vietnam, thereby squandering the achievement for which a million of our troops and countless numbers of civilians sacrificed their lives.”

His broadcasts and memoirs — which included details on the closely guarded private lives of Ho and other communist leaders — “created a sensation in Hanoi,” Vu said.

“His defection and revelations struck a heavy blow at the domestic legitimacy of the Party,” he added, “and was one of the main reasons the Party decided to release a huge collection of Party documents in the following decade to prove its accomplishments and to justify its continuing rule.”

Soon after arriving in Paris, Col. Tin told the New York Times he planned to stay for only a few months. But the Vietnamese government interrogated his wife and children, he said, and expelled him from the Communist Party. He never made it home, fearing for his safety.

Survivors include his wife, Le Thi Kim Chung of Hanoi; two children, Bui Bach Lien of Hanoi and Bui Xuan Vinh of Vancouver; four siblings; five grandchildren; and one great-grandchild.

In addition to criticizing the communist regime in Vietnam, Col. Tin called for greater understanding and assistance from the country’s former adversaries, including the United States.

When the U.S. Senate held hearings in 1991 on servicemen missing in action during the Vietnam War, he was among the star witnesses from Vietnam, testifying that no American POWs remained in the country.

“I am a soldier for 37 years,” he said in his testimony. “I have experienced pain and sadness of seeing my comrades disappear without any information about their tragic end. In Vietnam, there are 200,000 missing in action, and we have never found their remains. In my own family, two out of five are still missing. Being a soldier and also a member of an MIA family, I would like to take the opportunity to share the sadness and pain of the American POW and MIA families.”

He concluded his testimony with an embrace of Sen. John McCain (R-Ariz.), a retired Navy aviator who had been shot down during the war, tortured and held for nearly six years in prison. Col. Tin said he had met McCain, briefly, while doing research for a book about American POWs.