President of Ireland Michael D Higgins, right, presents a new coat to the Irish Guards wolfhound mascot as Prince Philip, Duke of Edinburgh gestures, at Windsor Castle on April 8, 2014 in England. (Peter Macdiarmid - WPA/Getty Images)

After a tense century of conflict, President Michael Higgins became the first Irish head of state to visit Britain since the Republic of Ireland fought to secede from the United Kingdom in 1916.

In a broadcast speech, Higgins said that Ireland and Britain had reached a friendship that "once seemed unachievable," and praised the two states' joint efforts toward creating peace in North Ireland, once ravaged by The Troubles - sectarian strife between Irish nationalists fighting for North Ireland to join the Republic of Ireland and unionists fighting to keep North Ireland under British rule.

Tension between Ireland and Britain still exists, but in recent years there has been considerable reconciliation between the two countries. Queen Elizabeth became the first British monarch to visit the Republic of Ireland three years ago.

Higgins did not shy away from the history between the two countries, visiting the tomb of the queen's cousin Earl Mountbatten, who was killed by an Irish Republican Army bomb. Northern Ireland's Deputy First Minister Martin McGuinness, a former IRA commander, will even join the Queen's banquet this evening.