The IRA’s killing of Lord Louis Mountbatten of Burma and 18 soldiers during one of the bloodiest days of the Troubles will be remembered in separate 40-year anniversaries later.
Provisionals blew up a fishing boat off the coast of Mullaghmore in Co Sligo in north west Ireland in 1979.
The decorated British Second World War commander was on board.
He was a second cousin to the Queen and served in two world wars, rising to Supreme Allied Commander of South East Asia.
He was also involved in the partition of India and the Suez crisis but retreated from high diplomacy and international relations to the relative isolation of his grand holiday home overlooking Ireland’s Atlantic coast.
Two members of the former First Sea Lord’s family and a Co Fermanagh teenager also died.
The bomb was detonated by remote control by republicans watching from the shore.
Mary Hornsey’s 15-year-old son Paul Maxwell was among the slain.
She will return to Mullaghmore on Tuesday for a cross-community memorial prayer service and will see for the first time a cross erected on the coastline close to where the blast happened.
It claimed four lives, Lord Mountbatten, Lady Doreen Brabourne, the 83-year-old mother-in-law of the earl’s daughter, his 14-year-old grandson Nicholas Knatchbull, as well as Paul who worked on the boat.
Just a few hours later, the IRA struck again, detonating two bombs at Narrow Water close to Warrenpoint in Co Down, killing 18 soldiers.
A memorial service will be held at the spot later.
There was also a 19th victim when William Michael Hudson, 29, a civilian visiting the Republic from London, was hit by a bullet fired by soldiers across the Newry River to where he was standing with his cousin Barry Hudson, who was injured.
Lord Mountbatten was popular around Mullaghmore and often drew a crowd of visitors as he set off in his boat, the Shadow V.
Paul had been a pupil at Portora Royal School in Enniskillen, and was planning a career with the Royal Navy.