The Queen has offered her deep sympathy to everyone who has suffered in centuries of conflict between Britain and Ireland.
In a powerful and moving address in Dublin Castle the monarch spoke of the painful legacy of the past and the need to remember all those whose lives have been affected.
She said the relationship had not always been straightforward but stopped short of delivering an apology for Britain's actions in Ireland, saying looking back both nations could have acted differently.
The Queen, whose cousin Lord Mountbatten was blown up by the IRA off the County Sligo coast in 1979, said: "It is a sad and regrettable reality that through history our islands have experienced more than their fair share of heartache, turbulence and loss.
"These events have touched us all, many of us personally, and are a painful legacy. We can never forget those who have died or been injured or their families.
"To all those who have suffered as a consequence of our troubled past I extend my sincere thoughts and deep sympathy.
"With the benefit of historical hindsight we can all see things which we would wish had been done differently or not at all."
The Queen opened her address welcoming her host President Mary McAleese in Irish, "A hUachtarain agus a chairde" - president and friends.
Her speech came midway through her state visit to the Irish Republic during which she laid separate wreaths in honour of the men and women who died fighting the British for independence and for the 49,000 Irish soldiers killed in the First World War. The ceremonies took place at the Garden of Remembrance in the centre of Dublin and the Islandbridge National War Memorial.
Dissident republicans protested as she was on her feet, but police kept them well away from Dublin Castle where the 172 guests included politicians and churchmen on all sides in Northern Ireland and the Republic. The only party not represented was Sinn Fein.