8 May 1916: Con Colbert, Michael Mallin and Seán Heuston were all executed by firing squad on this day for their part in the Easter Rising. They were executed in the Stonebreakers Yard of Kilmainham Jail Dublin.

Con Colbert: Born in 1888, Colbert was a native of Limerick. Prior to the Easter Rising he had been an active member of the republican movement, joining both Fianna Éireann and the Irish Volunteers. A dedicated pioneer, Colbert was known not to drink or smoke. As the captain of F Company of the Fourth Battalion, Colbert was in command at the Marrowbone Lane distillery when it was surrendered on Sunday, 30 April 1916.

Michael Mallin: A silk weaver by trade, Mallin was born in Dublin in 1874. Along with Countess Markievicz, he commanded a small contingent of the Irish Citizen Army, of which he was Chief of Staff, taking possession of St. Stephen’s Green and the Royal College of Surgeons.

Seán Heuston: Born in 1891, he was responsible for the organisation of Fianna Éireann in Limerick. Along with Con Colbert, Heuston was involved in the education of the schoolboys at Scoil Éanna, organising drill and musketry exercises. A section of the First Battalion of the Volunteers, under the leadership of Heuston, occupied the Mendicity Institute on south of the Liffey, holding out there for two days. Heuston Railway station in Dublin is named after him.
www.taoiseach.gov.ie

Prior to his execution Heuston was attended by Father Albert, of the Capuchin Order in his final hours. Father Albert wrote an account of those hours up to and including the execution:

“… I had told him in his cell that I would anoint him when he was shot. We now proceeded towards the yard where the execution was to take place; my left arm was linked in his right, while the British soldier who had handcuffed and blindfolded him walked on his left. As we walked slowly along we repeated most of the prayers that we had been saying in the cell... Having reached a second yard I saw there another group of military armed with rifles... A soldier directed Seán and myself to a corner of the yard, a short distance from the outer wall of the prison. Here there was a box (seemingly a soap box) and Sean was told to sit down upon it. He was perfectly calm, and said with me for the last time: ‘My Jesus, mercy.’ I scarcely had moved away a few yards when a volley went off, and this noble soldier of Irish Freedom fell dead. I rushed over to anoint him; his whole face seemed transformed and lit up with a grandeur and brightness that I had never before noticed.”
Father Albert concluded:

“Never did I realise that men could fight so bravely, and die so beautifully, and so fearlessly as did the Heroes of Easter Week. On the morning of Sean Heuston's death I would have given the world to have been in his place, he died in such a noble and sacred cause, and went forth to meet his Divine Saviour with such grand Christian sentiments of trust, confidence and love.
Piaras F. Mac Lochlainn, Last words : letters and statements of the leaders executed after the rising at Easter 1916, Dublin: Stationery Office.