Remembrance Sunday: Irish ambassador lays wreath in London
The Irish ambassador to the UK, Daniel Mulhall, has laid a wreath at the Cenotaph in London on Remembrance Sunday.
The invitation was made by the British government last month. Fifty thousand Irish men died in World War One.
The UK government said it recognised "the immense contribution and shared sacrifice" of thousands of Irish people who served in British forces.
The Queen is leading the Remembrance Sunday commemorations on 9 November.
It is the first time since 1946 that a representative from Ireland has participated in a wreath laying ceremony in London.
The DUP MP Nigel Dodds also laid a wreath at the Cenotaph in London.
Meanwhile, Secretary of State Theresa Villiers laid a wreath on behalf of the government at the Cenotaph at Belfast City Hall.
She was joined by Irish Foreign Minister Charlie Flanagan.
Taoiseach (Irish prime minister) Enda Kenny laid a wreath on behalf of the Irish government at a ceremony in Enniskillen. It was the third year he had attended the event.
Speaking afterwards, Mr Kenny said: "Enniskillen has a certain poignancy because of the IRA bomb here and because I've met some of the survivors and I think of those who spoke at the time about it - Gordon Wilson and some of the others.
"So there's a certain poignancy about Enniskillen and I think it's significant to have the taoiseach able to come to Enniskillen and it's a privilege to do so for the third year in a row."
Historians have estimated that more than 200,000 Irish-born soldiers served in the British Army and Navy from 1914 to 1918.
Thousands of soldiers also left the country and the Irish army to join British forces during World War Two.
During her historic visit to the Republic of Ireland in 2011, the Queen laid a wreath at the Republic of Ireland's Garden of Remembrance.
In July of this year, the Irish president paid tribute to Irish soldiers who fought in World War One.
Michael D Higgins joined the Duke of Kent and Northern Ireland Secretary of State Theresa Villiers at a commemoration in Dublin.
They dedicated a cross of sacrifice at Glasnevin Cemetery to mark the 100th anniversary of the outbreak of the war.
A military band, made up of musicians from Irish Army and British Army bands, performed at the ceremony.