IT was a day which shook the British establishment to its core, as one of its most prominent members was cut down by a terrorist's bomb.

Just before noon on 27 August 1979, the noise of a powerful explosion rang out over the calm waters off the village of Mullaghmore in Ireland, signalling a deadly new chapter in the IRA’s campaign of violence and sending shockwaves out across the world.

The target and victim of the blast was Louis Mountbatten, Earl of Burma, uncle to Prince Philip, second cousin to the Queen, mentor to Prince Charles and elder statesman of the Royal Navy.

His 14-year-old grandson Nicholas, 15-year-old deckhand Paul Maxwell, and Doreen Knatchbull, the dowager Baroness Brabourne and mother of Mountbatten’s son-in-law, John, also lost their lives.

It was a political assassination which demonstrated the Republicans bloodthirsty intent to raise the profile of their struggle worldwide and draw attention to their cause by the most violent means possible.

HeraldScotland:

Prince Charles and the Duchess of Cornwall visit the site where Louis Mountbatten died in 2015

And, followed just hours later by the killing of 18 soldiers in a brutal ambush in Warrenpoint, Northern Ireland, it provided the British with the starkest picture yet of the remorseless enemy they faced and the lengths they would go to to attack both the armed forces and high-profile figures.

 A veteran of both the First and Second World Wars, Mountbatten saw action in both the Atlantic and the Far East during a distinguished naval career which saw him rise to the rank of Rear Admiral.

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With close connections to the Royal Family, he moved in the very upper echelons of society and was personally wealthy through his own fortune and that of his wife, Edwina Ashley, a granddaughter of the Edwardian financier Sir Ernest Cassel.

The pair, who had two daughters, are said to have had an unorthodox marriage, with both taking several lovers. Mountbatten once quipped that "Edwina and I spent all our married lives getting into other people's beds."

Every year it was Mountbatten's custom to holiday at his summer home Classiebawn Castle, in Mullaghmore, a small seaside village in County Sligo, Ireland.

Despite the known threat of republican terrorism - the IRA had let it known he was in their sights - the 79-year-old Mountbatten discounted the danger, declaring:  "Who the hell would want to kill an old man anyway?"

HeraldScotland:

Louis Mountbatten's body returns to London

His overconfidence would prove fatal, but he had no way on knowing this when he took a party of family members and Paul Maxwell out on his fishing boat Shadow V to check lobster pots laid down the previous evening. 

On the trip were Mountbatten's grandsons Nick and Tim Knatchbull, their parents John and Patricia and Lady Brabourne, as well as the family Dachshund Twiga.

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From the shore they were watched through binoculars by two IRA men - one of them believed to be Thomas McMahon - who had placed a bomb in the boat's engine compartment the night before. It would be detonated remotely at 11.46 am.

The detonation was heard across the bay, as far away as Classiebawn. At once, other boats sped towards the scene, where a rising mushroom cloud of smoke was seen rising over the wreckage of the Shadow V. 

All those aboard were thrown into the water, badly injured. Mountbatten was knocked unconscious by the blast and drowned, though his legs were nearly severed and it is unlikely he would have survived. 

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Peter McHugh in Mullaghmore harbour

Peter McHugh, then aged in his early 20s, was among the locals who took to the water to rescue any survivors.

"It's hard to forget, I was just preparing to get ready for my day's work in the hotel when we heard the explosion," he said.

"I had never heard a bomb explode before other than on TV. It was quite a significant noise and I thought initially it might have been a gas cylinder exploding but it became apparent very quickly that it wasn't.

"We did what we could at the scene, and came back to the harbour and waited for the boats who had lifted the casualties to come into the jetty and started to take them to shore. We made up some crude stretchers to bring the people from the boats and some of the casualties were tended to in the foyer of the hotel here."

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Mr McHugh said no one had expected Lord Mountbatten would have been targeted, adding the village was left "totally shocked" by the tragedy - the only time Northern Ireland's Troubles ever touched it.

"There is shock even to this day that something like that could have happened in a quiet village like Mullaghmore," he said.

The IRA was quick to claim responsibility for the attack, describing it as an "execution" in a statement, which continued: "This operation is one of the discriminate ways we can bring to the attention of the English people the continuing occupation of our country."

The assassination, and the Warrenpoint ambush, were also celebrated as retaliation for the Bloody Sunday shootings, which saw British forces gun down 13 people during a demonstration.
Graffiti appeared in republican areas declaring "13 gone and not forgotten, we got 18 and Mountbatten".

HeraldScotland:

Mary Hornsey with a portrain of 15-year-old Paul Maxwell

But Mary Hornsey, 15-year-old Paul Maxwell's mother, believes the 27th August should also be known as Bloody Monday, with the assassination considered a war crime.

She said: "When I think back to that day, my memory is the sheer horror of the whole thing. It is just something we never thought would have happened.

"It was just awful, thinking that men had watched these young teenagers getting on a boat, and quite intentionally they pressed that button and killed them, children."

She added: "Some people have actually said that was a war crime, and I think they are right because they knew these children were on the boat, yet they set out to do it. That certainly was a war crime and I feel it should be treated as such.

"I think people can be brainwashed and I think they must have been brainwashed in order to do these dreadful things."