On 11 November 1920, King George V acted as Chief Mourner at the funeral of the First World War's Unknown Warrior.
The procession stopped at the new Cenotaph, or emblematic 'empty tomb', which completely caught the grieving nation's mood, and the King laid his wreath of white flowers on the memorial.
And Sir Edwin Lutyen's simple stone memorial remains the focus of the UK's annual salute.
Ever since 1920, in what became known as the National Act of Remembrance, each monarch has gathered the political and military leaders of our nation to reflect upon the high cost of peace, freedom and democracy.
The Queen has maintained this tradition throughout her reign and, with her signature adherence to form and proper order, it's one of those moments of unmissable certainty in the Royal calendar by which our watches of routine can be set.
Only occasionally have circumstances conspired to prevent Her Majesty from doing this duty in person.
This year too, she will continue this symbolic act – but, this time, she will not step into the parade but watch from a balcony.
For the first time in her 65-year reign she will be present but not lay her own wreath.
This small change of custom has caught the attention of many, though I doubt many can be greatly surprised.
Rather than stand alone, in front of her family, in the centre of Whitehall waiting for the moment to take hold of her traditional but enormous wreath, Her Majesty will watch from the balcony as Prince Charles does it for her.
The Queen is 91 now and carrying a wreath up steps to stand against the stone is not without physical challenge. Stopping this duty must only surprise people for the fact she did not elect to stop doing it a decade ago.
Instead, she will watch from balcony of the Foreign and Commonwealth Office building and, as Prince Charles places it atop the step and takes a pace back to salute, the Queen will bow in debt to the Fallen.
This is what Queen Elizabeth, the Queen Mother always did.
For half a century, this Royal widow would hold a studied gaze of reflection, seemingly lost in memories: possibly of her war leader husband, George VI, or her older brother, Fergus, who was killed at the Battle of Loos in 1915. Meanwhile, she watched as her Scottish Equerry, who wasn't that much younger than her, stepped forward to put down her wreath.
On Sunday, it will be an Equerry who will do this for The Duke of Edinburgh. This will happen immediately after the Prince of Wales has placed the Queen's and before he returns to place his own iconic one, which is dominated with the three feathers badge of the Heir Apparent.
Throughout Sunday's brief ceremony, the Queen will be where she wanted to be, beside her husband.
We know why the Queen has made this decision this year.
She is 91 and Prince Philip is well into his 97th year. This summer marked the end of his public life but Remembrance is one of those iconic annual ceremonies that both seem set on attending together.
After all, the Queen and Prince Philip represent the wartime generation that fought and won freedom in the Second World War. They continue to represent the generation of our parents, or grandparents, that heard the sirens and bombers over our cities, served in the Armed Services and must have endured the loss of countless friends.
After they will watch as their four children and two of their grandchildren add tributes to the gradual cascade of poppies around the Cenotaph's base.
Then the Queen's 13th Prime Minister, Theresa May, will lay the Government's wreath, as Churchill did at the start of her reign and as Lloyd George did at the first of these ceremonies in 1920.
The nations of the Commonwealth then help to complete the circle of poppy red and, in so doing their names remind us all what 'world war' really meant, as all these far flung countries were then part of Britain's old empire.
Having stepped onto her balcony vantage point at seconds to 11am, just 25 minutes later the Queen will bow a second time to the Cenotaph before withdrawing to return home.
Thousands of veterans, some from the Second World War and also in their 90s, will then march past this square of emblematic white stone and leave it further anointed with their memories, salute and tributes of poppy red.
But chief among the broadening sea of wreaths will stand the Queen's, as if she had placed it there herself because, like her grandfather George V in 1920, she will have in every real sense.Let's