Assassination
At 9:45 am on September 9, 1942 at Ballyboden, Rathfarnham, County Dublin, O'Brien left his house and began getting into his car. As was customary among Gardaí, Detective Sergeant O'Brien was unarmed. Three IRA men, wearing trenchcoats and armed with Thompson sub machine guns, came up the drive and opened fire. The shots from the Thompson smashed the windows of his car, wounding him. He alighted and ran for cover to the gate but before reaching it, he was shot by a single round to the head.
Two of the assassins wrapped the Thompsons in their trenchcoats, mounted their bicycles, and rode towards Dublin. Future IRA Chief of Staff Charlie Kerins left on foot, leaving his bicycle behind.
According to author Tim Pat Coogan, "The shooting greatly increased public feeling against the IRA, particularly as the murder was carried out almost in full view of his wife. As she held her dying husband, she watched his assailants cycling past."
Detective Sergeant Denis O'Brien was survived by his wife, Anne, and two daughters, Fiona and Eithne.
Read more about this topic: Dennis O'Brien (policeman)