John O'Mahony(1815–1877)

John O'Mahony was born at Clonkilla House, Kilbeheny, in the Galtee mountain country of east County Limerick on 12 April 1815, son of a Catholic gentleman-farmer who held the family estate and had been the Catholic-Emancipation organiser of the parish. He was schooled at the Catholic Latin school at Hospital, at Carlow College, and at Trinity College Dublin, taking his BA in 1836 with the Trinity Gaelic-philology-and-history class prize for his work on the medieval Annals of the Four Masters.

The Trinity Gaelic-philology training was the foundation of his scholarly career and the source of the name he later gave the Fenian Brotherhood. He inherited the Clonkilla estate at twenty-six, managed it through the early Famine years while reading the Old-Irish manuscript texts becoming available in the Royal Irish Academy publications, and joined the Young Ireland Repeal faction in 1847, where he met Thomas Francis Meagher, John Mitchel, William Smith O'Brien and James Stephens.

The 1848 rising at Ballingarry broke the Young Ireland movement. O'Mahony, who had brought a contingent of Limerick Confederates to the Tipperary meeting-point, escaped over the mountains to the Wexford coast, took a Welsh fishing boat to Cardigan Bay, and from there a packet to Paris. He spent ten years there in the dense community of post-1848 European political exiles, alongside James Stephens and the Polish, Hungarian and Italian republican networks of the period.

He moved to New York in 1856 and on 17 March 1858 founded the Fenian Brotherhood with the core of Young Ireland exiles he had reassembled there. He named it for the medieval Irish Fianna warrior bands of the Old-Irish manuscript tradition he had been reading since his Trinity years, and constituted it as the diaspora-American counterpart of Stephens's Irish Republican Brotherhood in Dublin. He served as its head centre and built it, at its peak, to about two hundred thousand subscribed members across the Irish-American working class.

He continued the Gaelic scholarship through his American years, completing a translation of Geoffrey Keating's Foras Feasa ar Éirinn from the Old Irish, published in 1857, the standard English-language edition for a generation. He died in New York on 7 February 1877, sixty-one years old; his body was brought back to Ireland on a public-subscription fund and buried at the Fenian Plot at Glasnevin Cemetery, Dublin, near the graves of Parnell and Casement. The O'Mahony name, the west-Cork patronymic Ó Mathghamhna, he carried from a Galtee-mountain Limerick household into the foundation of the modern Irish-American republican movement.