The Prince of Wales will meet Sinn Fein president Gerry Adams and Martin McGuinness as he begins an emotional and historic trip to the west of Ireland where his great uncle Lord Louis Mountbatten was assassinated by the IRA.
One of the most poignants stops on the official four day visit to the Republic and Northern Ireland will be on Wednesday when Prince Charles arrives in Mullaghmore, Co Sligo, the site of the atrocity.
Sinn Fein tonight confirmed both Mr Adams and Mr McGuinness would be meeting Prince Charles during trip.
Declan Kearney, chair of the party, said: "This was agreed to promote the process of resolving past injustices and promoting reconciliation and healing."
Earlier, gardai said the security threat against the royal visitors was 'moderate'.
"Our threat level is pitched at moderate, meaning an attack is possible but not likely. We have no specific intelligence relating to any specific threats. Having said that we won't take anything for granted," said a spokesman.
All of Ireland's main political leaders have been invited to National University Ireland Galway but the prospect of the visit beginning with the first meeting of a royal and a Sinn Fein leader in the Irish Republic will undoubtedly set the tone.
It also follows Mr McGuinness shaking hands with Queen Elizabeth in Belfast in 2012.
Charles, who is said to be excited by the prospect of his first official visit to Ireland in 13 years, will be in Mullaghmore on Wednesday following a service of peace and reconciliation at St Columba's Church, in nearby Drumcliffe.
The village is synonymous with the murder of his great uncle Lord Mountbatten on August 27 1979
The 79-year-old cousin of the Queen was targeted by the IRA as he set off with family and a local teenager to gather lobster pots and fish for shrimp less than 600m from the harbour of the normally peaceful fishing village.
Lord Mountbatten was murdered along with Lady Doreen Brabourne, the 83-year-old mother-in-law of the earl's daughter, his 14-year-old grandson Nicholas Knatchbull and 14-year-old Paul Maxwell, from Killynur, Enniskillen.
The meeting with Mr Adams ahead of a visit to the site of his great-uncle's murder and combining it with the themes at the prayer service a few miles away is widely seen as the next phase in ever deepening relations, friendships and bonds between the UK and Ireland.
Joined over the four days by the Duchess of Cornwall, Charles will also visit the grave of Irish poet WB Yeats who is buried under the shadow of Benbulben.
On the eve of the trip, Foreign Affairs Minister Charlie Flanagan said: "The visit programme celebrates the depth and potential of 21st century Irish-British links, while also acknowledging more difficult moments from the past."
"I recall that the Prince of Wales had made peace and reconciliation central themes in his previous official visits in 1995 and 2002, both of which came during important stages of the Northern Ireland Peace Process.
"Reconciliation and dealing with the past are issues that can still challenge us, and were the subject of the Stormont House Agreement reached in Belfast last December. We are now working hard to realise the potential of that agreement."
Mr Flanagan acknowledged the personal side of the trip and added: "Above all we will celebrate the strength of Irish-British relations today."
It will be the royal couple's first official engagement in Ireland but not the first time in the country for either of them as both have visited many times in a personal capacity including the Prince's trips to the Duke of Devonshire's Lismore Castle in Co Cork.
Charles was last in the Republic on formal business in 2002 and had previously been in the country in 1995.
Despite that the visit is no less historic. The invitation to the west of Ireland was extended after the Prince and Duchess welcomed President Michael D Higgins and his wife Sabina on an official trip to Britain last year.
The list of engagements begins tomorrow at the university where the city's and the college's links with Britain will be marked.
Charles will then attend the Marine Institute where he will be met by Taoiseach Enda Kenny before travelling south to the Burren in Co Clare, an ancient and dramatic stony outcrop famed for its rare plant life, biodiversity and archaeology.
Both engagements will allow the Prince to highlight environment and conservation projects.
That night they will join President Michael D Higgins and his wife Sabina for a private dinner in Lough Cutra Castle.
The royal couple will travel to Sligo on their second day, beginning with a civic reception featuring performances of Irish poetry and music and a viewing of the Niland Art Collection at the Model contemporary arts centre before moving on to the local institute of technology.
The significant engagement at Mullaghmore follows with the royals having an opportunity to meet with some of those who rescued the Mountbatten party.
On May 21, the royals will arrive in Northern Ireland where engagements include a reception and concert featuring performers from the region at Hillsborough Castle.
Charles and Camilla will visit Mount Stewart house and gardens and mark the completion of a three-year restoration programme.
They will also visit Corrymeela, Northern Ireland's oldest Peace and Reconciliation centre, which celebrates its 50th anniversary this year and the return follows the Prince's trip to the centre in 1998.