Manus O'Donnell

Manus Ó Domhnaill, anglicized Manus O'Donnell (died 1564), was an Irish clan leader, son of Hugh Duff O'Donnell. He was an important member of the O'Donnell dynasty based in County Donegal.

Hugh Dubh had been king (Rí) of the O'Donnells during one of the bitterest and most protracted of the feuds between his clan and the O'Neills, which in 1491 led to a war lasting more than ten years. He left his son to rule Tyrconnell (spelled in Irish as Tír Chonaill), though still a boy, when he went on a pilgrimage to Rome about 1511. On his return from Rome in broken health after two years' absence, his son Manus, who had proved himself a capable leader in defending his country against the O'Neills, retained the chief authority. When Hugh Dubh appealed for aid against his son to the Maguires, Manus made an alliance with the O'Neills, by whose assistance he established his hold over Tyrconnell. But in 1522 the two great northern clans were again at war.

Conn Bacach O'Neill, 1st Earl of Tyrone, was determined to bring the O'Donnells under his rule. Supported by Munster and Connacht, and assisted also by English contingents and by the MacDonnells of Antrim, O'Neill took the castle of Ballyshannon, and after devastating a large part of Tyrconnell he encamped at Knockavoe, near Strabane. Here he was surprised at night by Hugh Dubh and Manus O'Donnell, and routed with the loss of 900 men and an immense quantity of booty in the Battle of Knockavoe. Although this was one of the bloodiest ever battles between the O'Neills and the O'Donnells, it did not end the war; and in 1531 O'Donnell applied to the Lordship of Ireland for protection, giving assurances of allegiance to King Henry VIII.

...
Wikipedia