The nation will fall silent later as the King leads a moving Remembrance Day service for the first time as monarch.
A two-minute silence will take place across the UK at 11am and wreaths will be laid by members of the royal family, senior politicians and faith representatives at the Cenotaph in London.
Charles will lay a new poppy wreath incorporating a ribbon of his racing colours, with the design a tribute to the ones used by both his late mother and his grandfather George VI.
As he leads the nation at the Cenotaph for the first time as King, the service will be a poignant moment for the royal family.
The Queen, who died nine weeks ago at the age of 96, considered Remembrance Sunday, which commemorates the war dead, one of the most significant and important engagements in the royal calendar.
The then Prince of Wales (now King Charles III) lays a wreath during the Remembrance Sunday service at the Cenotaph, in Whitehall, London. Peter Nicholls
The nation’s longest-reigning monarch, who lived through the Second World War as a teenager and was head of the armed forces, only missed seven Cenotaph services during her reign, including in 2021 due to a back sprain.
A wreath will also be laid on the Queen Consort’s behalf for the first time as Camilla watches from the balcony of the Foreign, Commonwealth and Development Office building.
Around 10,000 Royal British Legion veterans, representing 300 different Armed Forces and civilian organisations, will take part in a march past.
They will be joined by an estimated 10,000 members of the public who will line Whitehall to watch the service.
Among those marching will be 100-year-old Second World War veterans and those who served in recent conflicts including in Afghanistan.
To commemorate the 40th anniversary of the Falklands War, 400 members of the South Atlantic Medal Association will march past the Cenotaph.
They will also be joined by bereaved family members with the youngest marcher aged eight.
Buckingham Palace has announced the Prince and Princess of Wales, the Earl and Countess of Wessex, the Princess Royal and Vice Admiral Sir Tim Laurence, the Duke and Duchess of Gloucester, the Duke of Kent and Princess Alexandra will attend the service on Sunday.
In 2017, Charles began placing a wreath on his mother’s behalf as she watched from the Foreign Office balcony.
The change was seen as a subtle shift of head-of-state duties.
The wreaths which the Queen, then then Prince of Wales (centre) (now King Charles III) and the then Duke of Cambridge (right) (now the Prince of Wales) Steve Parsons
Prime Minister Rishi Sunak said: “This year more than ever, we are reminded of the huge debt of gratitude we owe those who lay down their lives to protect their country.
“As we fall silent together on Remembrance Sunday, we will honour the memories of the men and women we have lost and pay tribute to the brave soldiers of Ukraine as they continue their fight for freedom.”
Defence Secretary Ben Wallace said: “Remembrance Sunday is a time to reflect upon the sacrifices made by our veterans and service personnel on operations around the world.
“We must never forget those who gave their lives in defence of our values and our great nation.
“All of us will also be thinking of those brave Ukrainians who are fighting for their very own survival to defend freedom and democracy for all, just as the UK and Commonwealth soldiers did in both world wars.
“Today, members of the UK Armed Forces at Cenotaph and around the world will come together to honour all those who came before them.”