Seán Heuston (1891-1916) was born at 24 Lower Gloucester Street, Dublin, the son of John Heuston, a clerk, and Maria McDonald. He was educated to intermediate grade by the Christian Brothers at O’Connell’s Schools on North Richmond Street. At the age of seventeen he joined the Great Southern and Western Railway Company as a clerk and was stationed in Limerick for six years. He joined Fianna Éireann, the scouting club for boys revived by Bulmer Hobson and Countess Markievicz in August 1909. He organised an extremely active branch in Limerick which eventually had a membership of 250 boys. He devoted most of his spare time to the organisation: lecturing, drilling, marching and promoting a high level of proficiency in the boys under his command.

In 1913 he was transferred to Dublin by the GSWR and assigned to the traffic manager’s office at Kingsbridge railway station (now Heuston station). He continued his work with Fianna Éireann where he met Con Colbert and Liam Mellows, both prominent in the organisation. He was given command of a branch in the north side of the city based in Hardwick Hall. He was promoted vice-commandant of the Dublin Brigade and also became director of training. Colbert and Patrick Pearse engaged him for Saint Enda’s, where he provided training in drill and musketry for the students. On the occasion of the landing of arms at Howth in July 1914, he led a contingent of Fianna, bringing a consignment of guns safely back to Dublin in a trek-cart.

Heuston joined the Irish Volunteers soon after their formation in November 1913, eventually becoming a captain in Ned Daly’s 1st Battalion. He worked hard with his company, organising marches and field manoeuvres, fostering a spirit of commitment and camaraderie, and procuring arms and equipment by purchase and any other means at his disposal. On Easter Monday he was assigned command at the Mendicity Institution, a building on the south side of the river Liffey, to the west of the Four Courts where Daly and the 1st Battalion were based. Heuston’s function was to control the route between the Royal Barracks (later Collins Barracks, now the National Museum of Ireland) and the Four Courts for some hours so that Daly and the remainder of the 1st Battalion would have time to settle in. In the event, Heuston and his force of less than 30 men held out for over two days. Surrounded and in a hopeless situation, Heuston surrendered on Wednesday to save the lives of his men.

Seán Heuston was tried by court-martial and sentenced to death. He was executed on 8 May. At twenty-five years and two months, he was the youngest of those executed. He was unmarried. He was survived by his mother and his brother Michael, then a student for the priesthood at the Dominican Priory, Tallaght.