Rep. Joseph Kennedy prepares to make his opening remarks at the transfer of the eternal flame ceremony on Tuesday at Arlington National Cemetery. The event celebrated the 50th anniversary of President Kennedy's visit to Ireland. (Maddie Meyer/The Washington Post)

One hundred fifty-five years ago, a barrelmaker named Patrick Kennedy boarded a ship at the quay at New Ross, Ireland, bound for America, where his great-grandson would become the most famous Irish American in history.

On Tuesday at Arlington National Cemetery, an Irish soldier in a dress-green uniform lit a torch from the eternal flame at the John F. Kennedy grave site. That torch will travel by plane, with special security permission, to Dublin, then by Irish navy ship to the New Ross quay, where it will light an eternal flame on a new monument to Irish emigrants.

President Kennedy’s visit 50 years ago this month to New Ross, where he was greeted by rapturous crowds, closed the circle on his great-grandfather’s journey to America. And Saturday’s torch-lighting will close another, bringing JFK’s flame to a nation that considers him as much Irish as American.

“This is the story of a young man returning home,” Rep. Joe Kennedy (D-Mass.), grandson of JFK’s brother Robert F. Kennedy, said at the Arlington ceremony. Under a sky that was Irish gray but Washington hot, he added: “It is a story of a thousand welcomes and a million tears, the story every immigrant holds in his heart.”

The grave site ceremony, the first time the JFK flame has ever been shared, is the latest in a year of Kennedy 50th-anniversary events, which will culminate with the unveiling of a new memorial in Dallas on Nov. 22 — the date of his assassination.

Lt. Col. Brendan Delaney, of the Irish Defence Forces, passes the eternal flame to Frank Stephens, a representative from the Special Olympics, on Tuesday at Arlington National Cemetery. (Maddie Meyer/The Washington Post)

In Dealey Plaza, on the grassy knoll that has become an almost mythic place in American culture, Dallas officials plan to unveil a plaque etched with the final paragraph of a speech Kennedy was planning to give that day, which read, in part:

“We in this country, in this generation, are — by destiny rather than choice — the watchmen on the walls of world freedom.”

Kennedy remains iconic in Ireland, where many people grew up with two photos in their living room: one of the pope and the other of JFK. His visit to Ireland in June 1963, on which he was accompanied by his sisters Eunice Kennedy Shriver and Jean Kennedy Smith (who later became U.S. ambassador to Ireland), was a watershed in Irish history: the homecoming of an Irish American who had become the most powerful man in the world.

The JFK flame’s journey comes as Ireland is trying to pull out of severe economic hardship after years of prosperity and as young people are once again being forced to leave to find work.

“We are fighting the good fight, and we will see the other end of it, and the inspiration of JFK is very important to us,” said Paul Kehoe, the minister of state at the Irish Department of Defense, who laid a wreath at the grave site at the late-morning ceremony.

“When John F. Kennedy came to Ireland 50 years ago, he gave an important speech about Ireland coming into modern times,” Kehoe said. “Ireland was seen in a different light after his visit. Ireland transformed itself, and I really believe it was because of JFK’s vision and inspiration.”

In his speech, Kehoe said Kennedy’s election as the first Catholic president was “living proof that Irish people could do anything they set their minds to do. . . . The glass ceiling was well and truly smashed.”

The transfer of the JFK flame is part of a year-long campaign in Ireland called “The Gathering,” which aims to lure people of Irish heritage back to the country for a visit.

The ceremony comes in one of the most remarkable weeks in U.S.-Ireland relations in years. While President Obama was meeting with his G-8 counterparts in Northern Ireland, first lady Michelle Obama and her two daughters toured Dublin on Monday and had lunch Tuesday at a pub with Irish rock star Bono and his family.

On Wednesday evening, Maryland Gov. Martin O’Malley (D) is scheduled to give a lecture in Dublin on relations between the two countries.

Then on Saturday in New Ross, in County Wexford in southern Ireland, Irish Prime Minister Enda Kenny will lead a ceremony in which the new flame is lit at the emigrants monument. A large contingent of the Kennedy family will attend, led by JFK’s daughter, Caroline Kennedy, and his only living sibling, Jean Kennedy Smith.

“This is a momentous occasion for our town,” said Paul Crowdle, chairman of the town council in New Ross, which has a population of 7,000. “Our connection with the Kennedy family will be reignited by this flame, and it will be everlasting.”

Crowdle, who came to Arlington, said he was born in September 1963, between Kennedy’s visit to Ireland and his assassination in Dallas. “So I can’t relate to his visit personally,” he said, “but our town has immense feelings going back to that day.”

Kennedy’s lasting allure for Americans was evident Tuesday morning as buses unloaded thousands of tourists who made the hot, sweaty walk up the hill to the JFK grave site and the adjacent burial sites of his brothers Robert and Edward M. Kennedy.

As a bagpiper played “Mist-Covered Mountain,” a lament that was performed at Kennedy’s funeral, hundreds of tourists in shorts and T-shirts, baseball caps and sneakers, stood in silent respect, many holding their smartphones high to capture video of the scene they had stumbled upon.

David and Mary Sue Richen, tourists from Oregon with L.L. Bean tote bags and New Balance sneakers, said they happened upon the ceremony by chance.

“The legacy that he has left to his country, it is just beautiful,” said Mary Sue Richen, whose grandmother emigrated from Ireland. “He showed people how to recognize your own beauty and skills.”

Timothy Shriver, chief of the Special Olympics and son of the late Sargent Shriver and Eunice Kennedy Shriver, greeted well-wishers after the ceremony. Shriver said he believed that people still visit his uncle’s grave because of “something bigger” than one man.

“These memories remind people of the United States as a place of service and deep and lasting connections with others,” he said. “People are still hungry for that. That’s why we still have all these people signing up for the Peace Corps and the Special Olympics. These are organizations founded on the principle that you can believe in something bigger than yourself.”

Shriver looked out over the crowds of tourists walking up the hill and said, “People are here by the thousands because they still want to believe in something like this.”

Kevin Conmy, an official at the Irish Embassy in Washington, said the torch lit Tuesday was one or four identical torches made from Irish ash wood carved with a likeness of JFK. He said the torches were modeled after those used to transport the Olympic flame for the 2012 London Olympics.

After the ceremony, Crowdle, the New Ross council chairman, stood holding the lighted torch, posing for pictures and looking slightly awestruck that he would be carrying it back to Ireland.