Shane O'Neill (C. 1530-1567) was a chieftain whose support was worth gaining by the English even during his father's lifetime; but rejecting overtures from the earl of Sussex, the lord deputy, Shane refused to help the English against the Scottish settlers on the coast of Antrim, allying himself instead with the MacDonnells, the most powerful of these immigrants.
Hugh then appealed to Shane O'Neill, who invaded Tyrconnel at the head of a large army in 1557, desiring to make himself supreme throughout Ulster, and encamped on the shore of Lough Swilly.
Conn was twice married, Shane being the son of his first wife, a daughter of Hugh Boy O'Neill of Clanaboy.
The fierce family feud only terminated when Matthew was murdered by agents of Shane in 1J58; Conn dying about a year later.
His second wife, Hugh's mother, by whom he was ancestor of the earls of Tyrconnel (see below), was Judith, sister of Conn Bacach O'Neill, ist earl of Tyrone, and aunt of Shane O'Neill.
Sussex had tried in 1561 to procure Shane's assassination, and Shane now laid the whole blame for his lawless conduct on the lord deputy's repeated alleged attempts on his life.
At last, in 1566, the queen placed the sword of state in Sidney's strong grasp. Shane was driven helplessly from point to point, and perished miserably at the hands of the MacDonnells, whom he had so often oppressed and insulted.
Thus the English government was committed to the cause of one who was at best an adulterine bastard, while Shane appeared as champion of hereditary right (See O'Neill).
Calvagh, however, died in the same year, and as his son Conn was a prisoner in the hands of Shane O'Neill, his half-brother Hugh MacManus was inaugurated The O'Donnell in his place.
This victory greatly strengthened Shane O'Neill's position, and Sir Henry Sidney, who became lord deputy in 1566, declared to the earl of Leicester that Lucifer himself was not more puffed up with pride and ambition than O'Neill.