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.]
O'CALLAGHAN, EDMUND BAILEY (1797–1880), historian, youngest son in a large family, was born in Ireland on 28 Feb. 1797, and there carefully educated. About 1820 he went for two years to Paris to study medicine. In 1823 he emigrated to Canada, and completed his student's career at Quebec, where he was admitted to practise in 1827. His wit and genial manner, combined with an earnest character and skill in his profession, soon attracted friends and brought him practice, and about 1830 he removed to Montreal.
O'Callaghan early took part in political life; in Quebec he had joined in organising the Society of the Friends of Ireland. At Montreal he took an active part at political meetings, and wrote political articles. In 1834 he became editor of the ‘Vindicator,’ the organ of the Canadian ‘patriots;’ and in 1835 was elected for Yamaska, in the assembly of Upper Canada, where he posed as one of the leaders of the revolutionary party, dressed in Canadian homespun, as their fashion was, in order to encourage home industries. On 6 Nov. 1835 the office of his paper was attacked and wrecked by members of the tory Doric Club. In October 1837 the revolutionary party met at Richelieu River to determine their final course of action, and O'Callaghan supported Papineau in condemning the resort to arms. When the crisis came, however, he took the field with others, and was in the action at St. Denis on 23 Nov. On the failure of the rising he fled with Papineau to the States, and on 29 Nov. 1837 a reward was offered for his apprehension as a traitor.
O'Callaghan found such a congenial home in New York that, when his companions returned to Canada under amnesty, he remained in the States, removing to Albany, where he practised as a doctor, and also edited the ‘Northern Light,’ an industrial journal. His interest in one of the current questions induced him to study the records of the State of New York, and, struck by the richness of the material buried there, he was led to investigate the old Dutch records. In 1846 he published the first volume of his ‘History of New Netherland, or New York under the Dutch.’ The work marked an epoch in the historical research of the United States; it was the first real history of New York State. Yet O'Callaghan lost money over the first volume, which he made up only by publishing the second himself in 1849. One of the immediate results of this work was J. R. Broadhead's mission to consult the archives of the chief European states for illustrations of the New York history. O'Callaghan was requested to edit the results of these labours, and eleven quarto volumes of ‘State Records, or Documentary History of the State of New York,’ 1849–51, with a full index, are a monument of his care and ability. It was while preparing this work that he called public attention to the value of the ‘Jesuit Relations,’ which he issued in 1847.
For some years O'Callaghan was attached to the office of the secretary of state, and edited the old colonial archives. In 1870 he was induced, much against his will, to remove to New York, and undertake the translation and arrangement of the municipal archives; but the corporation treated him badly, first cramping him for money, and afterwards declining to continue the work. After 1877 he was, owing to an accident, confined to his house, No. 651 Lexington Avenue, New York. He died on 29 May 1880.
O'Callaghan was a Roman catholic and a member of the Catholic Union of New York. Religious and earnest, he was a donor to St. Mary's Church at Albany. In 1846 he was made honorary M.D. by the university of St. Louis, and later LL.D. by St. John's College, Fordham, Massachusetts.
[Notice by John G. Shea in Mag. of American Hist. 1880, vol. ii.; Dominion (Canada) Ann. Register, 1880; M. Garneau's Histoire du Canada, iv. 272.]
