It was a sombre moment of reflection, where a tender gesture from a prince to a grieving toddler stood out starkly.
More than five decades have passed since Prince Philip was photographed alongside former US First Lady Jackie Kennedy, the Queen and others at the inauguration of Britain's Kennedy memorial at Runnymede in England.
As the royals, Jackie and other dignitaries stand, their gazes fixed ahead, the left hand of a small child, John F Kennedy Jr, clasps the Duke of Edinburgh's hand.
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© GettyQueen Elizabeth II and Prince Philip with Jackie Kennedy and her children John Jr and Caroline during the inauguration of Britain's Kennedy memorial at Runnymede in 1965.
The duke, dressed in a dark suit and tie, frames the toddler, his mother Jackie beside him. It is perhaps the place where the late US President, John F Kennedy, might have stood.
The photo was taken on May 15, 1965, almost two years after JFK's 1963 assassination.
It resurfaced online this week after author Paul Brandus shared an anecdote from the book The Death of a President about Philip following the royal's death last week aged 99.
Brandus recalled the strength Philip had shown the toddler just hours after JFK - considered at the time the head of "America's royal family" - was killed.
Video: Prince Philip's funeral details released (Sky News Australia)
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© GettyThe most poignant moment of the JFK funeral as three-year-old John Kennedy Jnr. stands at salute.
"The weekend of the Kennedy assassination, [Philip] flew to Washington for the funeral," Brandus posted to Twitter.
"At the White House on Sunday November 42, 1963, Jacqueline Kennedy was looking for John Jr and opened the door to his playroom.
"She found the Prince sprawled on the floor, playing and laughing with the murdered president's son.
"Days from his third birthday, John had said earlier that he 'didn't have anybody to play with' (also: 'where's Daddy?') and Her Majesty's husband decided that he would entertain the boy."
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© GettyQueen Elizabeth with JFK and Jackie Kennedy.
Prince Philip's compassion would be shown on the world stage again in 1997 when he stood shoulder-to-shoulder with his son, grandsons and Princess Diana's brother at her funeral.
The British royals first met with the former US president and his wife, Jackie, in June 1961 at Buckingham Palace.