Dermot Gallagher (72) who passed away on Sunday was a former secretary general at the Department of Foreign Affairs and was Irish Ambassador to the US from 1991 to 1997 at a key time for the peace process.
It was during Gallagher’s time in DC that President Bill Clinton made history by becoming the first US president ever to become involved in Northern Ireland.
Gallagher had a warm personal relationship with the president which was an important access point for Ireland.
After retirement Gallagher continued in public service serving on the board of many organizations and chairing the oversight commission of the Irish police force.
A native of Carrick-on-Shannon in County Leitrim, Mr Gallagher spent 40 years in government service as a diplomat and in senior positions in government departments. He was given a four-year extension beyond the usual retirement age as Secretary General of Foreign Affairs, an indication of how valuable his service was viewed by the government.
President Michael D Higgins has led the tributes.
In a statement, he said: "Mr Gallagher dedicated a lifetime to public service, serving with distinction as Ambassador to the United States and making a significant contribution to the peace process in Northern Ireland."
Minister for Foreign Affairs Charlie Flanagan said it was perhaps in the area of Northern Ireland and the peace process that Mr Gallagher made his greatest contribution.
He said: "As a young diplomat, he was part of the government's negotiating team at the Sunningdale talks in 1973 and many years later he was a major figure in the negotiation of the Good Friday Agreement."
Saddened by the passing of former DFAT SG, Dermot Gallagher. He will be remembered as a distinguished diplomat & for his key role in the GFA— Charlie Flanagan (@CharlieFlanagan) January 15, 2017
Fianna Fáil leader Micheál Martin said Mr Gallagher "has left an indelible mark on the diplomatic and public service landscape".
Sinn Féin president Gerry Adams said Mr Gallagher was a "proud Leitrim man who gave a lifetime of service to the Irish state as a civil servant".
Former junior minister and former senator Martin Mansergh, who was also involved in the peace process, said Mr Gallagher had as "emollient style of negotiation and diplomacy".
With profound sadness, Amb Anderson & the Embassy express our deepest condolences on the death of Dermot Gallagher, diplomat extraordinaire pic.twitter.com/gC06OBxrIF— EmbassyofIrelandUSA (@IrelandEmbUSA) January 15, 2017