Leaders and public figures from across North America paid tribute to Prince Philip and sent messages of sympathy to Britain's Queen Elizabeth on Friday after the death of her husband at the age of 99.
Queen Elizabeth, usually with her husband by her side, played a key role in fostering the so-called special relationship between Britain and the US and has met 12 serving presidents since she took the throne in 1952.
"Prince Philip gladly dedicated himself to the people of the UK, the Commonwealth, and to his family," President Joe Biden said in a statement.
The US president lauded Prince Philip for his decades of service to the UK and his involvement with military causes.
"The impact of his decades of devoted public service is evident in the worthy causes he lifted up as patron, in the environmental efforts he championed, in the members of the Armed Forces that he supported, in the young people he inspired, and so much more."
In subsequent remarks at the White House, the 78-year-old Mr Biden said: "Ninety-nine years old, he never slowed down at all, which I admire the devil out of."
President Biden was not the only US leader to send his condolences.
"Over the past few years, Melania and I were honoured to have the opportunity to visit the United Kingdom," former president Donald Trump said in a statement. "We saw firsthand how the Monarchy epitomises and carries on the virtues of the British People -- and no one did so more than Prince Philip."
Former President George W Bush also spoke fondly of how the prince "represented the United Kingdom with dignity and brought boundless strength and support to the sovereign.”
Mr Bush said he and his wife "are fortunate to have enjoyed the charm and wit of his company, and we know how much he will be missed".
In the US, which rejected the monarchy in 1776, a fascination with the British royals endured over the centuries. Interest has only grown since the marriage of the Californian actress Meghan Markle, now the Duchess of Sussex, to Prince Philip's grandson, Prince Harry.
In a short note on the couple's website, they said Prince Philip would be "greatly missed".
Former president Barack Obama released a statement in which he reflected fondly on meeting the queen and the Duke of Edinburgh, saying, "The queen and Prince Philip immediately put us at ease with their grace and generosity, turning a ceremonial occasion into something far more natural, even comfortable. Prince Philip in particular was kind and warm, with a sharp wit and unfailing good humour."
Canadian Prime Minister Justin Trudeau described the Duke of Edinburgh as a "man of great service to others" who always sought the best in people "and challenged them to strive for greater heights".
Canada is a member of the Commonwealth of Nations, formerly known as the British Commonwealth, a group of 54 countries that were almost all once part of the British Empire.
“Over the years [he] became colonel‑in‑chief of six Canadian units. In 2011, he was named honorary general of the Canadian Army and the Royal Canadian Air Force, as well as honorary admiral of the Royal Canadian Navy,” Mr Trudeau said.
Mr Trudeau said Prince Philip would be "fondly remembered as a constant in the life of our queen – a lifelong companion who was always at her side offering unfailing support as she carried out her duties".
Over the years, Prince Philip made at least 70 trips to Canada.
His last visit was in 2013, during which he picked up his insignia for the Companion of the Order of Canada, the country’s highest distinction, and commander of the Order of Military Merit from former governor-general David Johnston.
Former US president Bill Clinton also sent his family's condolences.
"We enjoyed every opportunity we had to visit with him through the years and will always be deeply grateful for the kindness he showed us."
At the UN, Secretary General Antonio Guterres said Prince Philip had "capably supported the queen in her duties as sovereign for over 60 years", according to a statement from a spokesman.
"He was known for his dedication to charitable causes as a patron of some 800 organisations, in particular those focused on the environment, industry, sport and education."