President Michael D Higgins is in Turkey today to join commemorations to mark 100 years since the disastrous Gallipoli campaign.
He will meet descendants of veterans and visit cemeteries for the fallen soldiers on the Turkish peninsula.
The amphibious attack was at that point the bloodiest in World War One.
Meanwhile, world leaders are also attending ceremonies commemorating the massacre 100 years ago of 1.5 million Armenians by Ottoman Turks.
The event, around the time of the First World War, is viewed by historians as genocide but modern Turkey, the successor to the Ottoman Empire, vehemently rejects the charge.
Russian president Vladimir Putin, French president Francois Hollande and other world leaders and dignitaries assembled this morning at the Tsitsernakaberd memorial complex in the Armenian capital, Yerevan.
Each leader walked along the memorial with a single yellow rose and put it into the centre of a wreath resembling a forget-me-not, a flower that was made the symbol of the commemoration.
Earlier, Turkey’s president insisted his nation’s ancestors had never committed genocide.
Addressing a meeting billed as an international peace summit, Recep Tayyip Erdogan said: “The Armenian claims on the 1915 events, and especially the numbers put forward, are all baseless and groundless.
“I say, we’re ready to open our military archives. We have no fear, no worries on this subject. Our ancestors did not persecute.”
Hundreds of Mr Erdogan’s supporters also attended, boisterously cheering and applauding his words and giving the event the feel of a campaign rally six weeks before Turkey’s elections.