On 27 August 1979, Lord Mountbatten, great uncle to Prince Charles, was blown up at sea by the IRA off the coast of Mullaghmore, Sligo.
Three others were killed on the boat that day, including two teenage boys. The bomb was detonated via remote control by republicans watching from the shore.
That moment would lead to a collision between the Royal Family, the heart of the British establishment and Irish republicanism.
Later that afternoon, in a second strike, the IRA killed 18 British soldiers and one civilian during the Warrenpoint ambush in what was the biggest single loss that the British army experienced in Northern Ireland.
After the death of Mountbatten, the IRA issued a statement which said: "The IRA claim responsibility for the execution of Lord Louis Mountbatten. 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 death of Mountbatten and the tributes paid to him will be seen in sharp contrast to the apathy of the British Government and the English people to the deaths of over three hundred British soldiers, and the deaths of Irish men, women, and children at the hands of their forces."
These events have been reexamined this week following the release of Season 4 of The Crown on Netflix. As fans of the drama will know, the show accurately portrays the seismic impact that Lord Mountbatten (played by Charles Dance) had on the formative years of Prince Charles (played by Josh O'Connor).
The first episode of Season 4 deals with Mountbatten's death and in a message that was posted to Twitter, Councillor Deirdre Conroy said: "‘Young people of Ireland’ ... if you’ve time to watch the new series of The Crown on Netflix, see this in Sligo in 1977 - children murdered by IRA onwards up to Omagh. Try and learn where Sinn Fein comes from instead of emailing other councillors with your demands."
In response to the message from the Fianna Fail Councillor for Dublin City, Dermot Lacey, Labour Councillor for Pembroke Ward on Dublin City Council, replied by saying: "Well said, Deirdre."
However, former Green Party member Saoirse McHugh was just one of the many people who were extremely critical and said: "To people in their 20s the 1970s may as well be the 1920s... ye have lost the plot altogether" before adding "my point is that FF have a bloody history too and every decade that passes their excuse 'that was a different time' has less and less meaning."
For those interested, Season 4 of The Crown is now available to watch on Netflix.
