The Queen led the nation in honouring members of the armed forces killed in conflict as Remembrance Sunday services took place around the country.
She was accompanied by the Duke of Edinburgh, other senior royals and members of the leading political parties at the Cenotaph in central London.
Also present was King Willem-Alexander of the Netherlands who laid a wreath following an invitation from the Queen to mark the 70th anniversary of the liberation of the Netherlands after the end of the Second World War.
In Belfast First Minister Peter Robinson and Secretary of State Theresa Villiers were joined by Irish Foreign Minister Charles Flanagan at the Remembrance Sunday ceremony at the City Hall.
Ms Villiers said: said: "In Belfast today with Northern Ireland's First Minister, the Lord Lieutenant of Belfast and the Irish Minister for Foreign Affairs, we remember the courage and sacrifice of this country's armed forces.
"Today's service was made particularly poignant as we approach 2016 and the centenary of the Somme which will have special resonance in Northern Ireland.
"We owe all the men and women who have served in the armed forces over the past hundred years a deep debt of gratitude."
Wreaths were laid at the foot of the Cenotaph in the grounds of the City Hall by the First Minister and the Secretary of State followed by representatives of the armed forces, veterans, PSNI Chief Constable George Hamilton and Deputy Lord Mayor of Belfast Guy Spence.
Irish prime minister Enda Kenny laid a wreath at the war memorial in Enniskillen, 28 years to the day after an IRA bomb attack killed 12 and injured 63 attending the Remembrance Sunday ceremony.
In London the Duke of Cambridge, Prince Harry, and the Duke of York also laid wreaths, as the Duchess of Cambridge, Queen Maxima of the Netherlands, the Countess of Wessex, and the Princess Royal's husband, Vice Admiral Sir Timothy Laurence, looked on from the Foreign Office balcony.
Prime Minister David Cameron was the first politician to lay a wreath, followed by Jeremy Corbyn who was wearing a poppy, and participated in the singing of the national anthem.
Mr Corbyn had previously attracted wide criticism for not singing the anthem at the Battle of Britain 75th anniversary commemorations.
Other members of the royal family, politicians, and high commissioners also laid their tributes as crowds lined Whitehall for the service, at the heart which was a two-minute silence marked at the beginning and end by the firing of an artillery gun.
Although cool and cloudy, the rain held off for the duration of the service and as thousands of veterans marched past the Cenotaph, before William took the salute at Horse Guards Parade.
Millions of people across the country fell silent in tribute to those lost in war, joining the crowds gathered in central London who stood in a moment of quiet contemplation as Big Ben struck 11am.
Later today giant falling poppies will be projected onto Parliament's Elizabeth Tower.
Thousands joined the Queen, a host of senior royals and Prime Minister David Cameron at London's Royal Albert Hall yesterday to honour the war dead and pay tribute to veterans from all conflicts in the annual event.
The service concluded with traditional prayers, hymns and blessings before an enthusiastic rendition of God Save The Queen.