(CNN) -- Britain's Queen Elizabeth II arrived in Northern Ireland Tuesday for a two-day diamond jubilee visit during which she will shake hands with a former IRA commander, Martin McGuinness, in a highly symbolic gesture.
She will meet McGuinness, now a Sinn Fein politician and the deputy first minister of Northern Ireland, at an arts event in Belfast Wednesday.
The meeting is a sign of the significant easing of tensions in British-Irish relations since the Good Friday peace deal was signed in 1998. Ireland's President Michael Higgins will attend the same event.
On Tuesday, the queen was greeted in Enniskillen -- the scene of a deadly IRA bombing in 1987 -- by crowds lining the streets and waving Union flags.
She was greeted by Secretary of State for Northern Ireland Owen Paterson, who accompanied her to a jubilee thanksgiving service at St. Macartin's Cathedral, an Anglican church, that was attended by more than 700 people.
She also went to a smaller service at St. Michael's Church in Enniskillen, a Catholic church.
Friday's confirmation that the queen would meet McGuinness prompted wide reaction in the UK media.
It follows the queen's visit to the Republic of Ireland in May of last year, which was seen as ushering in a new era in relations.
The meeting has an added significance for the queen because one of her relatives, Lord Mountbatten, was killed by an IRA bomb in 1979. IRA members have also killed police officers and soldiers in Northern Ireland, who serve in the queen's name.
The nationalist community in Northern Ireland sees the British as occupiers and wants their rule in the province to end.
Sinn Fein President Gerry Adams acknowledged the controversial nature of the handshake in a statement Friday.
"Because this involves Martin meeting the British monarch, this will cause difficulty for Republicans and nationalists who have suffered at the hands of British forces in Ireland over many decades," he said.
However, he said, the party had agreed that McGuinness should meet the queen "in the context of conflict resolution and national reconciliation, as well as our own republican national objectives."
The event is not connected with the queen's diamond jubilee celebrations, he said.
"This is a significant initiative involving major political and symbolic challenges for Irish republicans," Adams added.
"As the record of the peace process demonstrates, Irish republicans have frequently been prepared to take bold and historic initiatives and risks for peace to break stalemates and find agreements."
The Queen's 2011 visit to Ireland was the first by a British monarch to the republic since it gained independence in 1921 and marked a reconciliation between neighboring countries, which once viewed each other with suspicion and hostility.
McGuinness has admitted that he was a leader of the Provisional IRA during the 30-year conflict in Northern Ireland between pro-British and pro-Irish forces.
In recent years, he has received death threats from hardline dissident IRA splinter groups because of his support for the peace process.
The majority of the island gained independence in 1921, following two years of conflict, but six of the nine counties of the province of Ulster chose to stay in the United Kingdom, eventually becoming the country of Northern Ireland.
In the late 1960s the conflict between mainly Protestant unionists who want Northern Ireland to remain part of the United Kingdom and largely Roman Catholic nationalists who want the North to be reunited with the rest of Ireland exploded into a political and sectarian war, known as the Troubles.
The three decades of ensuing violence between the IRA and loyalists claimed the lives of more than 3,000 people, most of them north of the border, and while the Good Friday Agreement of 1998 effectively ended the conflict, suspicions remain.
Under the terms of the landmark accord, terrorist groups on both sides dumped their weapons, and political allies of the two now work together in Northern Ireland's power-sharing government.
CNN's Max Foster contributed to this report.