the first of the O'Neills to emerge as leaders of the native Irish as a result of England's attempts to subjugate the country in the 16th century.

Conn, who was related through his mother to the Earl of Kildare (Fitzgerald), became chief of the Tyrone branch of the O'Neills (Cinel Eoghain) about 1520. When Kildare became viceroy in 1524, O'Neill consented to act as his swordbearer in ceremonies of state; but his allegiance was not to be reckoned upon. However, the territory of Tyrone having been invaded in 1541 by Sir Anthony St. Leger, the English lord deputy, Conn delivered up his son as a hostage, attended a parliament held at Trim, and, crossing to England, made his submission at Greenwich to Henry VIII, who created him Earl of Tyrone for life. He was also made a privy councillor in Ireland and received a grant of lands. This event created a deep impression in Ireland, where O'Neill's submission to the English king and his acceptance of an English title were resented by his clansmen and dependents.

The resulting feud was aggravated by the nomination of Conn's illegitimate son Matthew as his heir, with the title of Baron of Dungannon. Matthew's parentage was actually in doubt, and in addition this nomination by the king was contrary to the Irish law or custom of tanistry. Matthew was murdered by followers of Conn's son Shane in 1558, and Conn died the following year. Elizabeth I settled the chieftainship on Shane but gave the earldom to Matthew's son Hugh.