HUGH O'NEILL (d. c. 166o), son of Owen Roe's brother Art Oge, and therefore known as Hugh Mac Art, had served with distinction in Spain before he accompanied his uncle, Owen Roe, to Ireland in 1642. After the death of Owen he defended Clonmel in 165o against Cromwell, on whom he inflicted the latter's most severe defeat in Ireland. In 1647 he so stubbornly resisted Ire ton's attack on Limerick that he was excepted from the benefit of the capitulation, and, after being condemned to death and reprieved, was sent as a prisoner to the Tower. He was released in 1652, and died, some time after 166o, probably in Spain.
The Clanaboy (or Clandeboye) branch of the O'Neills de scended from the ancient kings through Neill Mor O'Neill, lord of Clanaboy in the time of Henry VIII., ancestor (as mentioned above) of the Portuguese O'Neills. Neill Mor's great-great grandson, Henry O'Neill, was created baronet of Killeleagh in 1666. His son, Sir Neill O'Neill f ought for James II. in Ireland, and died of wounds received at the battle of the Boyne. Through an elder line from Neill Mor was descended Brian Mac Phelim O'Neill, who was treacherously seized in 1573 by the earl of Essex, whom he was entertaining, and executed together with his wife and brother, some 200 of his clan being at the same time massacred by the orders of Essex. (See ESSEX, WALTER DEVEREUX, 1st earl of.) Brian Mac Phelim's son, Shane Mac Brian O'Neill, was the last lord of Clanaboy, and from him the family castle of Edenduffcarrick, on the shore of Lough Neagh in Co. Antrim, was named Shane's Castle. He joined the rebellion
of his kinsman Hugh, earl of Tyrone, but submitted in 1586.
In the 18th century the commanding importance of the O'Neills in Irish history had come to an end. But John O'Neill (1740 1798), took an active part in debate in the Irish parliament, being a strong supporter of Catholic emancipation. He was one of the delegates in 1789 from the Irish parliament to George, prince of Wales, requesting him to assume the regency. In 1793 he was raised to the peerage of Ireland as Baron O'Neill of Shane's Castle, and in 1795 was created a viscount. In defending the town of Antrim against the rebels in 1798 O'Neill received wounds from which he died on June 18, being succeeded as Viscount O'Neill by his son Charles Henry St. John (1779-1841), who in 1800 was created Earl O'Neill. Dying unmarried, when the earldom therefore became extinct, Charles was succeeded as Viscount O'Neill by his brother John Bruce Richard (178o-1855), a general in the British army; on whose death without issue in 1855 the male line in the United Kingdom became extinct. The estates then devolved on William Chichester, great-grandson of Arthur Chichester and his wife Mary, only child and heiress of Henry (d. 1721), eldest son of John O'Neill of Shane's Castle.