Neil Sheehan, the Vietnam War correspondent and Pulitzer Prize-winning author who obtained the Pentagon Papers for The New York Times, leading the government for the first time in American history to get a judge to block publication of an article on grounds of national security, died on Thursday at his home in Washington. He was 84.

Susan Sheehan, his wife, said the cause was complications of Parkinson’s disease.

Mr. Sheehan, who covered the war from 1962 to 1966 for United Press International and The Times, was also the author of “A Bright Shining Lie: John Paul Vann and America in Vietnam,” which won a National Book Award and a Pulitzer in 1989. Reviewing it in the Times, Ronald Steel wrote, “If there is one book that captures the Vietnam War in the sheer Homeric scale of its passion and folly, this book is it.”

Intense and driven, Mr. Sheehan arrived in Vietnam at age 25, a believer in the American mission. He left, four years later, disillusioned and anguished. He later spent what he described as a grim and monastic 16 years on “A Bright Shining Lie,” in the hope that the book would move Americans finally to come to grips with the war.

“I simply cannot help worrying that, in the process of waging this war, we are corrupting ourselves,” he wrote in The New York Times Magazine in 1966. “I wonder, when I look at the bombed-out peasant hamlets, the orphans begging and stealing on the streets of Saigon and the women and children with napalm burns lying on the hospital cots, whether the United States or any nation has the right to inflict this suffering and degradation on another people for its own ends.”

Mr. Sheehan’s readiness to entertain the notion that Americans might have committed war crimes prompted Daniel Ellsberg, a former Defense Department analyst who had turned against the war, to leak the Pentagon Papers, a secret government history of American decision-making on Vietnam, to him in 1971. The papers revealed that successive administrations had expanded U.S. involvement in the war and intensified attacks on North Vietnam while obscuring their doubts about the likelihood of success.