Since the coronation of Queen Elizabeth II in 1952, he has been the consort — kneeling before, standing beside and walking behind the sovereign. It has been a public role, but often an empty and frustrating one.
And in performing it, Prince Philip — the Queen's husband, the Duke of Edinburgh — has sometimes overshadowed himself with a number of vocal gaffes throughout the years.
Yet the prince has been credited for his particular interest in scientific and technological research and the environment and has been very vocal on those topics in his criticism of industry.
He's also keenly interested in youth issues. In 1956, he launched the Duke of Edinburgh's Award aimed at young people between 15 and 25, and made a point of encouraging disabled youth to participate in the program. In five decades, the program has drawn more than three million young Britons, making it one of the most successful youth programs in the world. In Canada, more than 37,000 young people are currently enrolled in the program.
Charles Anson, a former adviser to the Royal Family, says Philip's role has long been undervalued.
"I think he is a much underestimated man," Anson said. "I think he will be remembered as someone who made a major contribution in the way Prince Albert made a great contribution in Queen Victoria's reign."
Forced into exile
Philip was born a prince of both Greece and Denmark on June 10, 1921, on the dining-room table at his parents' home in Mon Repos, on the Greek island of Corfu.
Despite his birthplace, he has no Greek ancestry. His family tree includes members of the royal families of Denmark, Germany, Russia and Britain. His father was Prince Andrew of Greece, whose own father was the grandson of King Christian IX of Denmark. Philip's mother was Princess Alice of Battenberg, the eldest child of Prince Louis of Battenberg and the sister of Earl Mountbatten of Burma.
When the Greek monarchy was abolished, the one-year-old Philip and his family were forced into exile. The young Philip had to travel in a cot made from an orange box.
As a boy, he attended schools in England, Germany and Scotland before joining the Royal Naval College at Dartmouth, England, as a cadet in 1939.
Through his uncle Lord Louis Mountbatten, the 18-year-old Philip was introduced to British royal circles. It was at this age he first met a 13-year-old Princess Elizabeth, his third cousin: both had Queen Victoria as a great-great-grandmother.
But as war broke out, he turned his attention to his naval career and quickly rose through the ranks. At the almost unprecedentedly young age of 21, he was appointed first lieutenant (second in command) of the destroyer HMS Wallace, which took part in the Allied landings at Sicily.
Courting a young princess
When he returned home in January 1946, Philip, who had kept in touch with Elizabeth, began courting the young princess. Their engagement was announced 18 months later.
Although most of the public embraced the union, some were unhappy with Philip's un-British origins and many began referring to him as "Phil the Greek." He silenced those critics when he became a British citizen in 1947 and renounced his Greek royal titles. He became Lt. Philip Mountbatten.
He and Elizabeth were married on Nov. 20, 1947, in Westminster Abbey in a wedding that helped boost British spirits still recovering from the war. He was designated a royal highness, created a knight of the Garter and awarded the title duke of Edinburgh.
Assuming his new royal role, Philip continued to be appointed and promoted to different positions in the navy. By 1952, he had reached the rank of commander.
His naval career came to an end that year when, on a trip to Kenya, Princess Elizabeth received news that her father, King George VI, had died and that she had ascended to the throne.
As husband of the sovereign, Philip was not crowned at the coronation ceremony in 1953.
Although his active role with the navy was finished, he continued to have involvement in the armed forces. He was appointed admiral of the Sea Cadet Corps, colonel-in-chief of the Army Cadet Force and air commodore-in-chief of the Air Training Corps. In 1953, he also had the duties of admiral of the fleet, field marshal and marshal of the Royal Air Force.
In February 1957, he was awarded the dignity prince of the United Kingdom, and became known as Prince Philip, Duke of Edinburgh.
'British women can't cook'
While carving out an independent role from the Queen, he has also established a reputation for blunt and controversial quips.
In 1966, he sparked outrage when he said, "British women can't cook." During a royal visit to China in 1986, he described Beijing as "ghastly" and told British students: "If you stay here much longer, you'll all be slitty-eyed."
He told a Briton he met in Hungary in 1993: "You can't have been here that long — you haven't got a pot belly."
He also dismissed stress counselling for servicemen in a TV documentary on the 50th anniversary of D-Day, saying, "It was part of the fortunes of war. We didn't have counsellors rushing around every time somebody let off a gun, asking, 'Are you all right? Are you sure you don't have a ghastly problem?' You just got on with it."
While his quips can offend, Philip is praised for his direct honesty.
Prince William told the BBC in November 2004 that he admires his grandfather's occasional bluntness.
"He will tell me something I don't want to hear and doesn't care if I get upset about it. He knows it's the right thing to say."
Accused in Diana's death
Philip came under intense scrutiny after Diana, the ex-wife of Philip's son, Prince Charles, died in a car crash with her companion, Dodi Fayed, in 1997.
Philip and the rest of the Royal Family initially went into seclusion after the accident, but Philip later made a strong statement at Diana's funeral, walking with his family behind her casket as it was carried in a carriage through the streets of London.
After the funeral, Fayed's father, the powerful Egyptian businessman Mohammed Al-Fayed, blamed Philip for the crash. He accused Philip of ordering British secret service agents to kill Diana and Fayed because Philip didn't want Diana to marry a Muslim.
An inquest into the accident cleared Philip of any wrongdoing, blaming the crash instead on the negligent driving of Diana and Fayed's chauffeur and the paparazzi who were chasing them.
'My strength and stay all these years'
Although Philip reportedly has a heart condition, he maintains a busy pace and has enjoyed relatively good health. In June 2010, he underwent surgery on his left hand for carpal tunnel syndrome. He was treated in hospital in 2008 for a chest infection.
He serves as the president or patron of nearly 800 organizations, and he fulfills an average of 370 official engagements each year.
He's also an avid sportsman who enjoys sailing, cricket and carriage-driving. He used to enjoy polo, but says age has forced him to take up carriage-driving, which he jokingly calls a "geriatric sport."
Despite his busy schedule, he always accompanies the Queen on her Commonwealth tours and state visits overseas, as well as on tours and visits to all parts of the United Kingdom.
He is said to be steadfast in his support for her, spending his public life two paces behind his wife, but always ready to help when needed. Those who know the royal couple well say the Queen often defers to Philip in private.
During celebrations for her golden jubilee on the throne in 2002, the Queen took the occasion to offer her own tribute to the royal consort.
"He has quite simply been my strength and stay all these years," she told the crowds.
"And I and his whole family and this and many other countries owe him a debt greater than he would ever claim or we should ever know."