Irish president Michael D Higgins yesterday urged the world never to forget the terrible lessons of the RMS Lusitania tragedy in World War I and to cherish peace while supporting diplomacy.
President Higgins was speaking as almost 10,000 people joined with dignitaries from the US, UK and Germany in Cobh, Co Cork, to mark the centenary of the sinking of the Cunard flagship on May 7, 1915.
A total of 1,198 people died when the liner sank in just 18 minutes off the Cork coast after being struck by a single torpedo from the German submarine, U-20.
Just over 700 people survived.
A service is to be held at the Holy Trinity Church in Ballylesson near Shaw's Bridge in Belfast on Sunday to remember the Northern Ireland people who lost their life in the tragedy.
Mr Higgins told yesterday's memorial event: "The importance of recalling the horror of war is that it should press us all to cherish and nurture peace, to defend the role of diplomacy, and seek to have it extended to achieve peaceful resolution of conflicts.
"At a time when the world is once again facing conflict and dispute, the urgency of the work of maintaining peace between nations and peoples once again takes on a new importance."
Descendants of victims and survivors fought back tears as they gathered in Cobh for memorial ceremonies.
Cunard second engineer George Harrison (30) revealed his great-grandfather, George Little, was RMS Lusitania's third engineer.
"He was around 40 years old at the time and, while he survived the sinking, he contracted pleurisy from exposure in the sea and that was a factor in his death a few years later," he said.
George, with Cunard since 2006, said the wreath-laying by RMS Queen Victoria over the wreck site was "very emotional".
"I think we all realised precisely what was on the seabed beneath us," he said.
Descendants dropped single red roses into the sea.
UK resident, Jill Power-Forward, who lost her grandfather, William Affleck-Anderson, said: "He left two children aged just four and two years so it had an enormous impact on the family."