Neil Sheehan, the Irish American journalist who changed the Vietnam war

Cornelius Mahoney "Neil" Sheehan is the first character we see in director Steven Spielberg's award winning new film The Post.

"Who's the long hair?" one U.S soldiers asks another, pointing at Sheehan (who was 30 at the time) as the courageous Irish American journalist follows a platoon of young troops into conflict in the jungles of Vietnam.

It's a good question. Sheehan, now 81, is the Pulitzer Prize winning former New York Times reporter who revealed to the nation and the world that the war in Vietnam was built upon what he would later call a decades long, "bright, shining lie."

Historians and news reporters have revered him for decades, but thanks to The Post movie the general public is getting reacquainted with the courageous Irish American who went eye to eye with Richard Nixon and the United States Supreme Court to change the nations history.

In 1971, Sheehan received the scoop of a lifetime when Daniel Ellsberg, a former military analyst, brought him the damning Pentagon Papers, a top-secret history of the decision-making behind the Vietnam war commissioned by Defense Secretary Robert McNamara.

The report plainly revealed the lies that had been told to the American public by four administrations to ensure their continuing support for military operations and war.

Spielberg takes some liberties with the timeline and facts of the case for dramatic effect, but he carefully shows us how this blockbuster expose changed the course of American history.

The son of Irish immigrants Sheehan was born in Holyoke, Massachusetts, the son of Mary O'Shea and Cornelius Joseph Sheehan and raised on a modest dairy farm near. A gifted student, he later graduated from Harvard University with a B.A. in history (cum laude) in 1958.

After a stint in the army he spent two years covering the war in Vietnam as UPI's Saigon bureau chief. He had no idea at the time that the growing war would eventually shape the course of his career and life. In 1964 he joined The New York Times, returning to spend another year in Vietnam where the die was cast.

In the fall of 1966, he became the newspaper's Pentagon correspondent and in 1968 he began reporting on the White House, becoming a correspondent on political, diplomatic and military affairs.

In 1971, after Sheehan obtained the Pentagon Papers from Ellsberg, the Nixon administration tried hard to halt the publication, tipping the country toward a crisis. The case, titled The New York Times versus the United States, saw the Supreme Court ultimately reject the government's position in a landmark First Amendment decision. Sheehan's expose would later earn The New York Times a Pulitzer Prize.

Spielberg's new film gives more screen to Meryl Streep as Katharine Graham, The Post's redoubtable publisher, and Tom Hanks, who plays The Post's legendary editor Ben Bradlee, as the pair tussle over whether or not to publish the top secret papers.

But without Sheehan's reporting and The New York Times decision to run the story there would have been no story to tussle over.

"Journalism is really a fourth branch of government," Sheehan has famously remarked. His courageous example stands to us now in out own time, when the freedom of the press is under relentless attack from another short tempered president who would prefer to have no checks on his power.