Dictionary of National Biography, 1885-1900/O'Cahan, Donnell Ballagh
O'CAHAN or O'KANE, Sir DONNELL BALLAGH or ‘the freckled’ (d. 1617?), in Irish Domnhall na Cathain, Irish chieftain, was eldest son of Rory O'Cahan, who died on 14 April 1598, when Donnell succeeded to his possessions in Ulster. These were very extensive, and were situated chiefly round Dungiven, co. Londonderry. The O'Cahan was Tyrone's principal vassal or ‘uriaght,’ and had the privilege of inaugurating each successor to the O'Neill. Before the end of 1598 O'Cahan was in rebellion under Tyrone, in command of sixty horse and sixty foot; during the next four years O'Cahan, with his brother Rory, was actively opposing Sir Henry Docwra [q. v.] in Ulster, and more than once his lands were ravaged (cf. Bagwell, Ireland under the Tudors, iii. 362, &c.) After the siege of Kinsale he saw that the struggle was hopeless, and thinking, no doubt, that a timely return to allegiance would enable him to secure substantial advantages at Tyrone's expense, he gave in his submission to Docwra and suffered forfeiture of one-third of his lands. From that time he served on the English side, furnishing a force of 50 horse and 150 foot at his own expense. The lord deputy, Mountjoy, promised in return that O'Cahan should hold his lands direct from the crown; but before the promise was carried out Tyrone submitted, and received a fresh grant of all his lands. He now attempted to revenge himself on O'Cahan for his desertion, and demanded O'Cahan's submission, two hundred cows, and the promise of an annual rent; as a pledge for its fulfilment he took possession of a large district belonging to O'Cahan. On the other hand, O'Cahan maintained that as soon as he had performed certain services due to the O'Neill, he was as much lord of his own land as any English freeholder; but knowing that Tyrone was supported by Mountjoy, he submitted for the time, and signed an agreement withdrawing all claims to independence.
In 1606 George Montgomery, bishop of Derry, instigated O'Cahan to proceed at law against Tyrone, who was attempting further aggressions, and had driven off all the cattle he could find in O'Cahan's district. The government were now inclined to support Tyrone's chief vassals, who might prove a check upon his power, and O'Cahan felt sure of a favourable hearing; his request for the services of Sir John Davis [q. v.], attorney-general, was granted, and in May he laid his case before the deputy and privy council. At the trial Tyrone behaved with violence, and snatched from O'Cahan's hands the paper from which he was reading; an order was made that two-thirds of the lands should remain in O'Cahan's possession, while Tyrone should hold the remaining third until the question was decided; shortly afterwards Tyrone fled.
O'Cahan was knighted on 20 June 1607, and in the same year was a commissioner to administer justice in Ulster in place of Tyrone and Tyrconnell; but the removal of Tyrone gradually led to O'Cahan's assumption of a position of hostility to the government. He had territorial disputes with Montgomery, who had supported him against Tyrone, because he thought O'Cahan would be a less powerful neighbour; and his refusal to submit to the crown officers until a force had been despatched to compel him lent colour to Chichester's suspicion that O'Cahan was implicated in O'Dogherty's designs [see O'Dogherty, Sir Cahir]. His brothers actually joined in the subsequent rising, but O'Cahan took no part in it, as he had at his own request been placed in confinement at Dublin Castle. After five months' imprisonment Chichester asked leave to release him, but this was refused, and O'Cahan remained in Dublin Castle till June 1609, when he was indicted on six charges of treason. The failure of the government, however, to obtain a verdict against Sir Neill O'Donnell induced them to postpone O'Cahan's trial, and he was sent to London and imprisoned in the Tower. Here, in spite of his petitions and complaints of the illegality of the proceeding, he remained, attended by his wife, until his death, which apparently took place in 1617. O'Cahan married, firstly, a daughter of the Earl of Tyrone; her repudiation by O'Cahan was one of Tyrone's complaints against him (Hill, Macdonnells of Antrim, p. 219). Mary, daughter of Hugh MacManus O'Donnell, is said to have been a second wife of O'Cahan; but her matrimonial relations were very complicated. She is said to have been the wife in O'Cahan's lifetime of two other men, one of whom was Teige O'Rourke (Cox, Hibernia Anglicana, ii. 32). O'Cahan was succeeded by Rory, a younger son, according to O'Hart's ‘Irish Pedigrees,’ 1887, i. 624–5 (cf. Ulster Journal of Archæology, iv. 140–5, where Rory is confused with his father).
[O'Cahan's case is dealt with in great detail in the Cal. State Papers, Ireland, 1608–14, and notices of him are contained in the prefaces to these volumes; see also Gardiner's Hist. of England, chap. x. throughout; Carew MSS. passim; Annals of Four Masters, s. a. 1598; Dockwra's Narration in Celtic Society's Miscellany; O'Sullivan-Beare's Hist. Cath. Hib. Compendium; Fynes Moryson's Itinerary, pt. ii. pp. 226, 236, &c.; Stafford's Hibernia Pacata; Cox's Hibernia Anglicana; Carte's Ormonde, i. 25, 43; Walpole's Kingdom of Ireland, passim; Meehan's Fate of the Earl of Tyrone, passim; Hill's Macdonnells of Antrim and Montgomery MSS. passim; Miss Hickson's Ireland in the 17th Cent. i. 2, &c.; Bagwell's Ireland under the Tudors, vol. iii.]