Flood, Francis Xavier (‘Frank’) (1901–21), republican, was born 1 December 1901 at 6 Emmet St., Dublin, third son among eight sons and one daughter of John Flood, constable in the DMP, and Sarah Flood (née Murphy). Flood was educated at the CBS, North Richmond St., and from there gained a scholarship to study engineering at UCD. A diligent student, Flood passed the first two years of his course with distinction and took an active part in university life, being a member of the Literary and Historical Society. Influenced by his older brothers (especially Seán, who had fought in the 1916 rising), and against the wishes of his father, Flood joined the Dublin Brigade of the Irish Volunteers in 1917 and rose to become first lieutenant of H Company and a member of the brigade's active service unit.
From 1919 onwards Flood and his friend Kevin Barry (qv) combined their studies with increased participation in IRA activities, most notably the raid on the King's Inns (1 June 1920), in which a large quantity of arms and ammunition was captured. On 20 September 1920 Flood took part in the raid at Church St. during which three British soldiers were killed and Barry was captured. As a member of the brigade's active service unit Flood was involved in planning several abortive attempts to rescue Barry. On 21 January 1921 he led an attack on an RIC patrol at Drumcondra, but the attacking party was surprised by a large detachment of auxiliaries, and Flood and four others (Patrick Doyle, Bernard Ryan, Thomas Bryan, and Dermot O'Sullivan) were captured while trying to escape. The five were imprisoned in Kilmainham but transferred to Mounjoy in mid February.
Although there were no fatalities during the Drumcondra ambush, Flood and the other four were charged with the capital offence of high treason, and after a trial by court-martial all were sentenced to death. O'Sullivan, who was only 17, had his sentence commuted to life imprisonment. Despite widespread pleas for clemency the remaining four were executed by hanging on 14 March 1921, along with two other men, Patrick Moran and Edmond Foley. The Irish Trades Union Congress called a general strike for the morning of the execution and up to 20,000 people gathered outside Mountjoy. The resulting publicity greatly enhanced Sinn Féin's popularity and was a source of considerable embarrassment to the British administration. Flood, as with all of those executed in Mountjoy during 1920–21, was buried within the prison but, following a long campaign by the relatives, his remains – and the remains of Kevin Barry and eight others – were exhumed and given a state funeral to Glasnevin cemetery on 14 October 2001.