Britain's Royal Family and its Armed Forces have an intimate association that goes back centuries.
Of course, the Queen, as sovereign, is the official Head of the British Armed Forces.
While members of the British Army and Royal Air Force are required to pledge an oath of allegiance to the monarch, the Royal Navy is exempt from this, having been formed by the monarchy itself rather than Parliament, meaning that the oath is implicit.
Many members of the Royal Family have served in the military throughout Queen Elizabeth II's reign.
The Queen herself began her relationship with the British military when, in 1945, as a young princess, she joined the Auxiliary Territorial Service – making her the first female member of the Royal Family to join the Armed Forces as an active member.
Famously, the Duke of Edinburgh served in the Royal Navy, between 1939 and 1952, during which he was mentioned in dispatches for his actions during the Second World War. He rose to the rank of Commander.
Prince Charles also served in the Royal Navy, as well as training with the Royal Air Force. He was awarded his RAF wings at Cranwell on 20 August 1971.
Prince William served as a Regimental Officer in the British Army before undertaking attachments to the Royal Air Force and Royal Navy. This was until September 2008 when it was announced that he would train to become a full-time pilot with Search and Rescue (SAR).
Prince Harry had a distinguished military career. He served in the British Army for 10 years, during which time he rose to the rank of Captain and saw active service in Afghanistan on two separate tours.
Prince Andrew trained as a naval officer, receiving his pilot's wings in 1981. The following year, as a Royal Navy sub-lieutenant, he flew helicopter missions in the Falkland Island War. Retiring in 2001, he reached the honorary rank of vice admiral in 2015.
As well as being active members of the military, members of the Royal Family also hold an impressive collection of honorary titles.
Queen Elizabeth II: Ceremonial Colonel-in-Chief of the Commonwealth Armies and Air Commodore-in-Chief of Commonwealth Air Forces.
Prince Philip: Lord High Admiral of the United Kingdom and Field Marshal of the United Kingdom, Australia and New Zealand; Marshal of the Royal Air Force; Marshal of the Royal Australian Air Force; Marshal of the Royal New Zealand Air Force; Captain General Royal Marines; Colonel-in-Chief-The Royal Canadian Regiment; Colonel-in-Chief of the Army Cadet Force.
These titles were held before Prince Philip's death and will now be assigned by the Queen.
Prince Charles: Colonel-in-Chief Commonwealth Armies and Air Commodore-in-Chief of Commonwealth Air Forces; General/Admiral of the Fleet/Marshal of the Royal Air Force of the British Armed Forces; Honorary Commodore-in-Chief, Aircraft Carriers.
Prince William: Commodore-in-Chief of HMNB Clyde; Commodore-in-Chief of the Royal Navy Submarine Service; Commodore-in-Chief of Scotland; Honorary Air Commandant of RAF Coningsby; Colonel of the Irish Guards.
Prince Harry (Previously held before returning to Her Majesty): Canadian Ranger; Honorary Air Commandant of RAF Honnington; Commodore-in-Chief of Small Ships and Diving. He remains a patron of the Invictus Games.
While the role of the Monarchy has changed from ancient times when armies were actively lead by the sovereign – (King Harold was killed by an arrow to the eye in 1066) – the Royal Family remains actively involved in all branches of the military.
A Royal face will frequently be seen visiting the troops, thanking them for their service, and reminding them of the British values which define our military so much.