The Queen made the Duke of Edinburgh the Lord High Admiral of the Navy today to mark his 90th birthday.
The monarch has held the office of the titular head of the Navy since 1964 but today gave it to her husband as he celebrated his milestone age.
Philip gave up his promising naval career to devote his life to royal duty and support his wife in her role as Sovereign.
The office of the Lord High Admiral dates from the 14th century.
The birthday gift from the Queen could be seen as a touching acknowledgement of the sacrifices the Duke has made for his wife.
Had he not become the Queen's husband, some believe he would have been First Sea Lord, the professional head of the Royal Navy.
In a recent ITV interview to mark his 90th year, the royal was asked how he felt giving up his job as a Royal Navy officer.
"I don't know how difficult it was, it was naturally disappointing," he replied.
"I had just been promoted to commander and the fact was that the most interesting part of my naval career was just starting."
Philip joined the Navy after leaving school and in May 1939 enrolled at the Royal Naval College, in Dartmouth, where he was singled out as best cadet.
He rose rapidly through the ranks, earning promotion after promotion, but his life was to take a very different course.
The Duke's flourishing naval career came to a premature end in 1951.
The health of his father-in-law George VI was deteriorating and Queen-in-waiting Princess Elizabeth was required to take on more royal responsibilities.
Philip stepped down from his active role in the forces to fulfil his duty as her consort.
His wife acceded to the throne within the year when the King died in February 1952.
He has spoken of his fascination with the sea, describing it as "an extraordinary master or mistress".
Philip served on the battleship HMS Ramillies in 1940 in Colombo as a Midshipman and spent the following six months in the Indian Ocean.
In January 1941, he served on HMS Valiant in Alexandria and two months later was mentioned in dispatches for his actions during the Second World War.
He was in control of Valiant's search lights as it fought an Italian cruiser in the battle of Cape Matapan when he spotted an unexpected second enemy vessel nearby.
At the age of 21, he became one of the youngest officers in the Royal Navy to be made First Lieutenant and second-in-command of a ship and went on to become First Lieutenant of the new Fleet Destroyer HMS Whelp.
Whelp sailed for the Indian Ocean to join the British Pacific Fleet and Philip was in Tokyo Bay when the Japanese surrendered on September 2, 1945.
He was later given command of the frigate HMS Magpie in 1950.
Philip, known as "Dukey" to his men, described the period as the happiest days of his sailor life.
Although he gave up his career, the Duke has remained closely associated with service life.
In 1952, he became Admiral of the Sea Cadet Corps, Colonel-in-Chief of the Army Cadet Force and Air Commodore-in-Chief of the Air Training Corps and a year later became Admiral of the Fleet and appointed Captain General in the Royal Marines.
Neither the Army nor the Royal Air Force has an equivalent office to that of the Lord High Admiral.
The Queen, who is Head of the Armed Forces, took on the title after a review of the Navy's organisational structure in 1964.
The office, which was previously held by peers of the realm, dates from the 14th century when the Navy was consolidated into one force.
In 1628, following the death of the Duke of Buckingham, the position became honorary with the running the Navy delegated to a board of commissioners.
For a short time, mostly during the 17th century, it was was held by reigning monarchs including Charles II, James II and Queen Anne.
A Buckingham Palace statement said: "This gift to The Duke of Edinburgh on the occasion of his 90th Birthday keeps alive the tradition of the Monarch investing the office as an honour."
An official investiture ceremony for Philip will take place at a later date.
The First Sea Lord Admiral Sir Mark Stanhope, who is the professional head of the Royal Navy, welcomed the appointment.
"I would like to offer my sincere congratulations to His Royal Highness The Duke of Edinburgh on his assumption of the title Lord High Admiral," he said.
"His Royal Highness has a long association with the Royal Navy and we are enormously grateful for his support."