Britain's Prince Charles shook hands with Gerry Adams on Tuesday in his first meeting with the leader of the former political wing of the Irish Republican Army (IRA) that killed his great uncle in a bomb attack 36 years ago.
The pair exchanged a few sentences at a reception in the west of Ireland city of Galway, a day before Charles is due to visit a nearby site where the IRA killed Lord Louis Mountbatten in 1979.
The latest in a series of gestures of reconciliation between Britain and Sinn Fein, it was the first time Adams has met a senior member of the royal family.
The IRA ended its 30-year armed campaign against British rule in Northern Ireland as part of a power-sharing peace deal in 1998 between Protestants who want to remain loyal to the British crown and Catholics favoring unification with Ireland.
Northern Ireland has been largely peaceful since then but small splinter groups continue to launch attacks against British targets and security is tight for Charles's visit.
Three others, including a 14-year-old boy who was Charles's godson, were also killed when the IRA blew up a boat Mountbatten, who was a senior British military commander in World War Two, was using during a holiday in the region.
Charles in turn has long been a figure of hate among those in favor of a united Ireland because of his position as head of the British Army's Parachute Regiment, which played a key role in the Bloody Sunday shootings in 1972 in which 13 Roman Catholic civil rights marchers were killed.
Speaking ahead of the meeting, Adams said the visit was an opportunity for personal reconciliation.
"I have very little in common with a member of the British royal family, but at a human level ... (we) have an awful lot in common in terms of bereavement, suffering and, I would like to think, forbearance," Adams told Irish state broadcaster RTE.
"I will express regret, which I have done on many occasions. Anyone who wants a United Ireland has a duty to embrace this and to make friends with our neighbors," said Adams, who is now a member of the Irish parliament.
In 2012, Charles's mother Queen Elizabeth met Martin McGuinness, a former IRA commander and a senior member of Sinn Fein, a meeting seen as a landmark step in rapprochement in Northern Ireland.
(Writing by Conor Humphries; Editing by Michael Holden and Alison Williams)