For hours the young cadets waited, standing at attention by the freshly dug grave - a striking tableau in their crisp green tunics and brown breeches, rifles by their sides.
Fifty years later, they still remember how those hours felt like an eternity, the muffled beat of the distant drums growing steadily louder as the funeral procession crossed the Potomac River and entered Arlington National Cemetery.
They were closer to the grave than anyone, this specially chosen honor guard about to deliver the performance of their lives.
Opposite, a phalanx of press photographers from around the world jostled for position, training cameras on the 27 soldiers as reporters asked, "Who are those guys?"
The answer astounded them.
The cadets were from Ireland, fresh-faced 18- and 19-year-olds who, just a day earlier, had been whisked from their barracks on a remote, wind-swept plain in County Kildare to travel, along with Irish President Eamon de Valera, to Washington for the funeral.
With names like McMahon, Coughlan, Sreenan and O'Donnell, they hailed from towns and villages all over Ireland. Most had never been abroad, never been on a plane. Yet there they stood, a foreign army on American soil about to give a final, silent salute to a U.S. president with an Irish name: John Fitzgerald Kennedy.
Even today, they marvel at the fact that, in her darkest hour, Jacqueline Kennedy made a special request of the U.S. State Department: that the Irish cadets who had so mesmerized her late husband with a memorial drill for the dead during his visit to Dublin just months earlier, perform that same drill by his grave.
"This is not the land of my birth but it is the land for which I hold the greatest affection," Kennedy told the cheering throngs at the end of his historic four-day visit to Ireland in June of 1963.
His trusted adviser, the late Ted Sorensen, said, "The joy never left him."
Joy consumed Ireland, too, as it welcomed home its anointed son. Kennedy's great-grandfather had emigrated from County Wexford in 1849, and the Irish took an intensely personal pride in their connection to America's first Irish Catholic president.
From the stately chambers of Dail Eireann, the parliament in Dublin, to his ancestral home on a farm in Dunganstown, where he drank tea with relatives and broke away from his bodyguards to join a children's choir in a rousing rendition of "The Boys of Wexford," Kennedy received a rapturous welcome.
"Occasionally in the history of a country, a thing happens that means more than can be put quite into words," wrote Patrick O'Donovan in The Observer, a London newspaper. "The visit of President John Kennedy to Ireland was one of those things."
Kennedy himself wrote, in a thank-you letter to de Valera, that the trip had been one of the most moving experiences of his life. And a highlight, he said, was a wreath-laying ceremony by the graves of the leaders of the 1916 Easter Rising in Dublin.
As part of the ceremony, 26 army cadets, led by an officer, performed a special, silent drill in remembrance of the dead. The slow-moving solemnity and precision of their movements captivated Kennedy. The drill concluded with the cadets bowing their heads over their rifles, a gesture of quiet contemplation for the departed warriors.
"That is the finest honor guard I have ever seen," Kennedy told the officer in charge, Lt. Frank Colclough.
Back in Washington, Kennedy requested a film of their drill: There was some suggestion that he wanted to introduce elements of it to honor guards at Arlington.
By then the soldiers who had performed the drill had graduated, and so it fell upon the next class to make the film. For weeks, the cadets trained daily, practicing the 10-minute, intricately choreographed moves. Though it was an honor, some considered it a thankless task - all this practicing merely for a film.
It was also, in the eyes of at least one drill sergeant, an ominous one. The drill should only be performed for a memorial service or a burial, Sgt. "An Rua" (The Red) O'Sullivan warned the cadets.
It was bad luck, he said, to perform it for any other reason.
The Curragh is a flat, grassy plain in the Irish midlands, famous for its racecourse, its vast flocks of sheep and its military college. It is where Irish soldiers are trained to this day.
But the sprawling red-brick barracks was an isolated place for young men in the 1960s, where all orders were in Irish and the daily regimen of study, training and endless inspections was broken only by a weekly one-day leave.
Most cadets were on such a leave the night in 1963 that the late Col. Cyril Mattimoe, then commander of the barracks, received a startling phone call. It was 9:30 p.m. on Saturday, Nov. 23, the day after Kennedy's assassination. On the line was Lt. Gen. Sean MacEoin, Ireland's military chief of staff.
"You are providing a guard of honor at the funeral of President Kennedy," he told Mattimoe. "You have a busy night ahead."
In personal reflections written years later, Mattimoe described the chaotic hours that followed as messengers were dispatched to local cinemas and restaurants and frantic phone-calls were placed to dance halls 60 miles away in Dublin.
Cadet Jim Sreenan remembers the lights snapping on during the movie "Genghis Khan" and someone bellowing, "All cadets report back to base." Martin Coughlan recalls "all hell breaking out" as he was summoned back to the barracks from a dinner with friends.
After being briefed on their mission, the cadets had little time to contemplate its enormity. They spent the night in a whirlwind of preparations - degreasing their ceremonial Lee Enfield rifles, which had been packed away in storage, ironing their uniforms and practicing the drill until 2 a.m.
The next day, they boarded an Aer Lingus Boeing 707 with de Valera and other dignitaries, their rifles tucked under their seats. Each carried a few pound notes offered by a thoughtful local shopkeeper, who emptied his till on their behalf.
In Washington, the cadets were greeted by Secretary of State Dean Rusk and bused to the Fort Myer military base where, jet-lagged and overawed, they once again practiced.
"We were nervous and exhausted, and the drill was terrible," recalled Peter McMahon.
But the curious American G.I.s leaning out of the windows around the drill square thought otherwise.
"We of the Old Guard marveled at their deportment and precision drilling," Martin Dockery, one U.S. soldier, wrote in a piece for an Irish magazine in 2007.
Nor were there any ill feelings toward the special position offered the Irish.
"No one was offended," said Dockery, now retired and living in Rye, N.Y. "The drill was so unusual and so moving, we completely understood why Mrs. Kennedy had remembered them."
"All was uncannily still," Mattimoe wrote of the cadets' long, silent wait by the open grave. "Nature itself seemed sunk in grief."
Eventually, the cortege arrived and the Kennedy family walked to the grave. Heads of state moved in behind the cadets. Cardinal Richard Cushing began the prayers. A deafening flyover followed: Air Force and Navy jet fighters, and Air Force One.
And then, Colclough gave the order in Irish - "Ar Airm Aisiompaithe Lui" ("On Reversed Arms Rest") - and the cadets commenced their drill. Years later, they remember it as a near spiritual experience.
"It was all very haunting, but enveloping at the same time," said Michael McGrath. "It was like the drill just became part of you, and we all became one."
And though it passed in a blur, they knew they had executed it flawlessly.
Afterward, when they had marched away, the cadets found themselves surrounded by senators and congressmen, eager to thank them for their comportment and composure. Back at Fort Myer, their American peers took them out on the town, where everyone recognized Kennedy's Irish honor guard and strangers treated them to meals and drinks.
A hero's welcome followed in Ireland, with de Valera congratulating them individually.
Letters of praise poured into The Curragh from top American military officials. But the most moving expressions came from ordinary Americans.
"Your honor guard made me feel proud to tears," wrote Frank Gulland, who described himself as "just a salesman of building materials, from a small city in Ohio."
Wrote 11-year-old Jeff Hemus of San Diego: "I thought the Irish soldiers were real, real good."
Soon after returning from Washington, the cadets received a gift from their counterparts at Fort Myer - a large, framed photograph of their honor guard standing at attention at Kennedy's grave. The picture still hangs in the cadet mess at The Curragh.
On a visit to the barracks this summer, Coughlan and Sreenan reminisced as they gazed at the faded photograph, picking out their younger selves, pausing to remember colleagues who have passed. They pondered the irony of it - that in training for a film of the drill, specially requested by Kennedy himself, they had in fact been rehearsing for his funeral.
Over the decades, the cadets who became known as "Kennedy's Class" have remained close, hosting annual reunions and trips back to The Curragh.
They are planning a 50th anniversary visit to Arlington later this year. There, they hope to lay a wreath at Kennedy's grave. They will pause in a moment of reflection. And they will cast their minds back to that crisp November day, when, with the eyes of the world upon them, they performed the finest drill of their lives.