Taoiseach Micheal Martin has praised the "vital role" of the European Union in bringing peace to the island of Ireland, on the 50th anniversary of it joining the bloc.
Friday marked half a century since then-Taoiseach Jack Lynch and foreign affairs minister Patrick Hillery signed the treaty in Brussels that took the fledging state into the European Economic Community.
It laid the groundwork for a referendum in May 1972 which saw the Irish people vote by an overwhelming 83% in favour of joining the EEC, which was renamed the European Union in 1993.
In a speech at the National Archives marking the event, Mr Martin hailed the role of the EU in bringing peace and prosperity to Ireland.
He said: "A young Irish state transitioned from relative economic stagnation and insularity to embrace economic openness, a place at the heart of the single market, at a competitive and attractive location for global investment.
"We unleashed an energy of Irish creativity and entrepreneurial spirit without precedent.
"It was a transformation supported by our European partners, not least through substantial transfers of structural funding.
"Our European Union membership has also played a vital role in the journey towards peace and reconciliation on this island.
"For as long as the United Kingdom was a fellow member state, Europe provided a valuable shared space in which Irish and British ministers could co-operate and get to know each other.
"Relationships forged through this contact helped to develop the mutual trust and understanding that were so important throughout the peace process."
Mr Martin also praised the EU for its steadfast support for Ireland throughout the Brexit negotiations.
"They've stood by Ireland, as we have worked together to manage the challenges for this island, resulting from the United Kingdom's decision to leave the European Union," he said.
"Making the objective of sustaining peace avoiding a hard border and protecting the island economy a major priority from the very beginning of negotiations."
EU membership has given Ireland "a reach and an influence that we would not otherwise enjoy", he added.
Over the next 18 months, a series of events will mark the major milestones on Ireland's road to EU membership.
Mr Martin said: "We will take this opportunity to encourage reflection, debate and exchange on the Ireland-European Union relationship and how we can best contribute to a strong and shared future.
"Today is a day to celebrate our history in the European Union and be proud to be Irish, to be European."
