John Joseph Heuston (also known as Jack to his family) was born in Dublin in 1891. In 1908 he moved to Limerick City to work for the Great Southern and Western Railways (GSWR). In 1911 he played a significant role in establishing Na Fianna Eireann in Limerick. Within a year, thanks to Heuston’s efforts, the Barrington Hall Sluagh was one of the largest Fianna branches in Ireland. Around this time he was appointed to the National Fianna Council (or Ard Choiste) as Limerick representative.
By 1913 Heuston had returned to Dublin and began working at Fianna HQ. He was given command of a Fianna Sluagh, which was based in Hardwicke Street in the City. The following year Heuston took a prominent role in the Howth Gunrunning. Sean also joined the Irish Volunteers and became Captain of ‘D’ Company in the 1st Battalion.
Following the restructuring of the Fianna organization in 1915, Heuston was appointed to the National Fianna Executive and became ‘Director of Training’. He was appointed as Captain of the 6th Dublin Company (No. 6 Coy) and was vice-Commandant of the Fianna Dublin Brigade.
In 1916 Sean Heuston and a small group of young Irish Volunteers took over the Mendicity Institution on the Dublin Quays. Several of the Irish Volunteers at the Mendicity Institution with Heuston were also (or had been) members of Fianna Eireann including P. J. Stephenson, Sean McLoughlin, Liam Staines and Dick Balfe.
Following the surrender he was tried by court-martial and sentenced to death. He was executed on May 8th 1916. He was twenty five years old.