Queen Elizabeth has paid a solemn tribute to Ireland's war dead, laying a poppy wreath at the Islandbridge memorial in Dublin.
Politicians from all sides, senior churchmen and judges sat with army veterans for the commemoration on day two of the historic state visit.
The Queen placed a wreath before President Mary McAleese and both stepped back, bowed and observed a minute's silence broken by a piper playing a Scottish air.
Among the guests were former Northern Ireland secretary Peter Mandelson, Northern Ireland First Minster Peter Robinson, Catholic Archbishop of Ireland Sean Brady and the head of the Church of Ireland Alan Harper. Others invited included UDA commander Jackie McDonald.
The ceremony builds on the symbolic reconciliation in 1998 when the Queen and the President unveiled a tower on the site of the battle of Messines Ridge in memory of the Irish dead of the First World War, and to inaugurate the Island of Ireland Peace Park.
It was the first public event undertaken by an Irish and British head of state.
Islandbridge gardens contain a War Stone inscribed "Their Name Liveth For Evermore", and the 30ft Guillemont Ginchy Cross, the wall behind which bears the words in Irish and English:
"I ndil-chuimhne are 49,400 Eireannach do thuir sa Chogadh Mhor 1914-1918 - To the memory of 49,400 Irish men who gave their lives in the Great War 1914-18".
Again the Union flag flew along side the Tricolour and, to mark the role played by tens of thousands of Irishmen in the wars, three divisional flags of the British Legion.
The United Nations flag was also flown above the gardens..
The ceremony opened with a rendition of God Save The Queen and the Tricolour at half-mast. After the sounding of the Last Post, the flag was returned to full height and Amhran na bhFiann was played.
Following the wreath-laying, the Queen and the Duke of Edinburgh were shown illuminated manuscripts, created by stained glass artist Harry Clarke, in the granite room of the memorial containing the names of all the soldiers commemorated.
The Queen shook hands with Mr Robinson, SDLP leader Margaret Ritchie and Environment Minister Phil Hogan, while Tom Elliot, Ulster Unionist leader, Alliance leader David Ford and dignitaries from Messines and Ian Adamson, of the Somme Association, also attended.
The royal also met Finance Minister Michael Noonan.
Northern Ireland Deputy First Minister Martin McGuinness declined an invitation to attend the memorial service.