Traynor is an experienced soldier having been a member of the Boland’s Mill garrison during the 1916 Easter Rising. After the Rising he is interned in Frongoch internment camp, Wakefield Prison and Mountjoy Prison where he shares a cell with Seán Mac Eoin.
Traynor works as a boot maker and is married with ten children. At the time of his death the eldest is 18 years and the youngest 5 months. The eldest son, Frank, represents Ireland at the 1928 Summer Olympics in Amsterdam, competing as a bantamweight boxer.
Traynor is captured during an ambush on Auxiliaries in Brunswick Street, Dublin, on March 14, 1921, and is tried on April 5 at City Hall. He is part of a party of IRA volunteers keeping watch outside a meeting at 144 Brunswick Street that includes Seán MacBride. During the fight an IRA volunteer, Leo Fitzgerald, is killed, as are Constable James O’Farrell and Cadet Bernard Beard of the Dublin Metropolitan Police. Traynor is reportedly badly beaten by members of the Igoe Gang.
Traynor is hanged in Mountjoy Prison in Dublin on April 25, 1921, one of a group of men, commonly referred to as the Forgotten Ten, hanged in Mountjoy Prison from 1920–21, during the Irish War of Independence. He is 38 years old at the time of his death.
Mark Sturgis, assistant to the Under-Secretary for Ireland, writes, “Traynor, captured red handed with an attacking party when Auxiliaries were killed in Brunswick Street, was executed this morning. I don’t think they will make much fuss as there is no sort of ‘alibi’ business this time – nor is he the usual ‘youth’, dear to ‘The Freeman‘, as he is over 40 and has a pack of children, the poor deluded idiot.”
On the day following Traynor’s death, Gilbert Potter, a Royal Irish Constabulary (RIC) District Inspector based in Cahir, County Tipperary, and being held for Traynor’s safe treatment is executed in reprisal by members of the 3rd Tipperary Brigade of the IRA. Another IRA volunteer, Jack Donnelly, captured with Traynor, is sentenced to death but is reprieved by the declaration of an impending truce in June 1921.
In 1965 a statue is erected to honor Traynor in his native town of Tullow. The Ballad of Thomas Traynor is written in his memory.