DALLAS — A half dozen Irish soldiers toting guns with brilliantly polished bayonets formed a guard of honor outside the U.S. Embassy in Dublin as the U.S. flag was lowered to half-staff in one of several solemn ceremonies planned today to mark 50 years since the assassination of President John F. Kennedy in Dallas.

More than a dozen retired Irish army officers who, as teenage cadets, had formed an honor guard at Kennedy’s graveside, gathered in the front garden of the embassy in the heart of the Irish capital to remember the first Irish American to become leader of the free world.

Together with Irish Foreign Minister Eamon Gilmore and embassy staff, they observed a minute’s silence and lay two wreaths from the Irish and American governments in memory of JFK.

Similar events were planned for Boston, where the JFK Library and Museum will open a small exhibit of never-before-displayed items from Kennedy’s state funeral and host a musical tribute that isn’t open to the public, and in Washington, where President Barack Obama will meet privately at the White House with leaders and volunteers from the Kennedy-established Peace Corps program.

Dallas will mark the day with a solemn ceremony in Dealey Plaza, through which the president’s motorcade passed when shots rang out. That event will feature brief remarks by the mayor, the tolling of church bells and readings from the president’s speeches by author David McCullough.

In Dublin, an Irish army commander at the embassy drew a sword and held it aloft as a lone trumpeter played “The Last Post,” the traditional British salute to war dead. A bagpiper played laments including “Amazing Grace.” A U.S. Marine raised the flag again as the bugler sounded an upbeat “Reveille.”

All the while, busy Dublin traffic continued to pass by outside the iron-fenced embassy. The day was crisp, windless, with trees full of autumn leaves and a cloudless blue sky, the sun blindingly low on the horizon.

Gilmore paid tribute to JFK’s legacy and a fiddler who performed for Kennedy during his visit to the western Irish city of Galway on June 29, 1963, performed a lament and a jig. Frankie Gavin was aged 6 during the Kennedy visit and performed with his family’s band as the Kennedy motorcade passed through Galway.

A committee convened by current Dallas Mayor Mike Rawlings to plan the city’s event wanted to focus “in a positive way more on the legacy of President Kennedy,” said Ron Kirk, a former mayor and member of the panel.

About 5,000 tickets were issued for the free ceremony in Dealey Plaza, which is flanked by the Texas School Book Depository building where sniper Lee Harvey Oswald perched on the sixth floor. The U.S. Naval Academy Men’s Glee Club will perform in a nod to Kennedy’s military service and there will be an Air Force flyover. A moment of silence was at 12:30 p.m., when the president was shot.

The Coalition on Political Assassinations, a group that believes Kennedy’s death was part of a conspiracy, usually gathers on the plaza’s “grassy knoll” for a moment of silence each Nov. 22. Since it’ll be blocked off this year, executive director John Judge — who first came to Dealey Plaza for the fifth anniversary of JFK’s death in 1968 — said he’s reached a “livable” agreement with the city.

The group — which plans to wear specially made T-shirts with an image of Kennedy’s head with a bullet hole and blood and the slogan “50 years in denial is enough” — gathered a few blocks away and move to the plaza after the official ceremony ends.

In Boston, the private musical tribute featured Paul Winter, whose jazz sextet performed for Kennedy at the White House, along with a U.S. Navy choir and James Taylor. Other notable guests include Massachusetts Gov. Deval Patrick, who is scheduled to read quotes from Kennedy’s speeches.