O'More, Rory (d. 1655), politician, was the son of Calvagh O'More, whose family had lost their lands in the midlands during the Marian plantations of the mid sixteenth century. Calvagh had eventually settled in north Co. Kildare, but also possessed part of the ancestral property of Owen Roe O'Neill (qv) in Co. Armagh. Little is known of Rory's childhood or education, though he was an eloquent speaker, fluent in both English and Irish. His marriage, to a daughter of Sir Patrick Barnewall (qv) of Kilbrew, provided O'More with an extensive network of connections throughout the Pale. He first emerged on the national stage in 1641 as the instigator of the plot that would eventually lead to the outbreak of the Ulster rebellion later in the year. O'More contacted catholic leaders in Ulster, including Conor, Lord Maguire (qv), and Philip MacHugh O'Reilly (qv), MP for Co. Cavan, with a view to organising a revolt. Despite a possible conflict of interest over land, he also sent his parish priest, Toole O'Conley, to inform Owen Roe O'Neill of developments in Ireland and to solicit his support for military action. In September 1641 the conspirators decided to capture Dublin castle, while Sir Phelim O'Neill (qv), a late addition to the plot, would simultaneously seize a number of key strongholds in south Ulster. O'More travelled to Dublin, but their plan was betrayed by Owen O'Connolly and he fled the city after trying unsuccessfully to warn Maguire of the danger. Sir Phelim O'Neill, however, successfully captured Newry, and on 29 November the rebels, commanded by O'More and O'Reilly, wiped out a force sent from Dublin to relieve the town of Drogheda.
As the Ulster rebels advanced southwards, O'More helped arrange an historic alliance with their traditional enemies, the Old English of the Pale. At a public meeting on the Hill of Crofty in early December 1641, O'More's statement that the men of Ulster and the Pale were ‘of the same religion and the same nation’ (Gilbert, Ir. confed., i. 37) was greeted with wild applause. For the next six months he concentrated his energies on organising catholic forces throughout Leinster, working closely with Nicholas Preston (qv), Viscount Gormanston. In April 1642 he commanded a detachment of troops at Kilrush, Co. Kildare, where the rebels suffered a reverse at the hands of the royalist James Butler (qv), earl of Ormond. Two months later the confederate catholic association emerged from a meeting of lay and clerical leaders in Kilkenny. O'More served on the provisional supreme council, which sat until the first meeting of the confederate general assembly (October 1642). He played no major part in confederate government from that time onwards, however, which is perplexing given his central role in the formation of the association. Reports from the first assembly refer to the disquiet of O'More and his supporters, ‘supposing themselves despised in the disposition of the public ministry’ (Bourke, Clanricarde memoirs, 298). His close links with Owen Roe, who had returned to Ireland in July 1642, may possibly have worked against him, as the Ulster general was viewed with suspicion by many in Kilkenny.
Despite this disappointment, O'More tried to ingratiate himself with all the various factions in Kilkenny, working to maintain confederate unity. His nomination as a privy councillor, according to the terms of the first Ormond peace treaty (August 1646), suggests that he retained a certain degree of support in influential circles. When civil war erupted in the confederate association in 1648, O'More, by now a close advisor of Owen Roe, supported the papal nuncio GianBattista Rinuccini (qv) against the peace faction. Nonetheless, during the peace negotiations between Kilkenny and Ormond in late 1648, the confederate commissioners insisted that he be given permission to seek the recovery of the family estates in the midlands before the Irish parliament. A special clause to this effect was included in the second Ormond treaty, signed in January 1649. During the Cromwellian war he served as a military commander in both Connacht and Leinster, with full military and civil authority, but his lacklustre performance aroused much criticism. In 1652 he went to Inishbofin off the coast of Galway, one of the last catholic strongholds; but as the parliamentary forces approached, he made arrangements to flee. Walter Lynch (qv), bishop of Clonfert, sailed in the last ship to leave the island without waiting for O'More, who was forced to make his own way. He finally escaped into Ulster but died in obscurity in 1655 and was buried at Steryne churchyard, in the parish of Magilligan, Co. Londonderry. His brother Lewis, a colonel in the confederate army, was hanged for murder by the Cromwellians. Although declared innocent by the court of claims in 1662, Rory's son Charles experienced difficulties in recovering the estates, as the court expressed dissatisfaction with the proofs provided of his father's death. A daughter of O'More, Anne, was the mother of Patrick Sarsfield (qv), the famous Jacobite general.