11 May 1650: Lord Broghill advanced to the Irish held Carrigadrohid Castle taking along the captive Bishop of Ross, Boetius MacEgan, as a hostage. Broghill threatened to hang the bishop if the garrison did not surrender. When MacEgan bravely told the garrison to defy Broghill he was tortured and hanged in view of the castle. Broghill then offered lenient terms, which were accepted by the garrison commander, who was allowed to march away with his men.
11 May 1745: The battle of Fontenoy was fought in the Austrian Netherlands in present day Belgium. The French under Marshal De Saxe defeated the British - Dutch Army under the Duke of Cumberland. At a critical moment of the fighting the Marshal committed his reserves including the Irish Brigade to battle thus forcing the British to withdraw. The Irish Regiments advanced upon the British lines to the cry: 'Cuimhnigidh ar Liumneac, agus ar fheile na Sacsanach’ - 'Remember Limerick and British faith,' It was their most famous Victory.
11 May 1823 – Death of Rev. John Troy, O.P., Roman Catholic Archbishop of Dublin. Ordained a priest in 1762 Troy became Archbishop of Dublin in 1786. He laid the foundation stone of the Pro-Cathedral, Marlborough Street, Dublin in April 1815. Troy was an implacable opponent of the United Irishmen who favoured reaching an accommodation with the British Establishment re the practise of the Catholic Religion.
11 May 1853: The Boyne Viaduct, one of the architectural wonders of Victorian Ireland and built on the Dublin-Belfast railway line, carried its first train on this day. The viaduct was not fully completed until 1856.
11 May 1971: The death occurred of ex Taoiseach Sean Lemass on this day. Lemass fought in the 1916 Rising, the War of Independence and the Civil War. He was elected TD for Dublin South in 1924 but abstained from taking his seat and was a founding member of FF in 1926. He was appointed Minster for Industry and Commerce in 1932. During the Emergency (1941–5), his portfolio expanded to cover the Ministry of Supplies. In 1945, De Valera nominated him as Tánaiste, and he succeeded de Valera as Taoiseach in 1959. He is remembered for building up Ireland's industry and infrastructure and founded many state bodies to achieve this such as Bord na Móna, Aer Lingus and Irish Shipping. In his tenure as Taoiseach the State enjoyed uninterrupted economic growth and social and economic advancement. He applied for membership of the EEC in 1963 and tried to break the ice with the Unionists in the North in 1965 but neither came to fruition at the time. He led FF to victory in the 1965 General Election but did not gain an overall majority. He retired in 1966 and was succeeded by Jack Lynch.