Plunkett, St Oliver (1625–81), catholic archbishop of Armagh, was born 1 November 1625 at Loughcrew, near Oldcastle, Co. Meath, son of John Plunkett and Thomasina Plunkett (née Dillon). He had an elder brother, Edward, and three younger sisters, Catherine, Anne, and Mary. He was related on his father's side to the senior branches of the Plunketts (Lords Fingall, Dunsany, and Louth) and on his mother's side, through cousinship, to the earls of Roscommon and Fingall. He was tutored from his infancy to the age of 16 by his first cousin once removed, the Cistercian Patrick Plunkett (qv), later bishop of Ardagh (1647–69) and Meath (1669–79), on whose advice he travelled to Rome in 1647 with Fr PierFrancesco Scarampi (qv), former papal representative at the confederation of Kilkenny. Sir Nicholas Plunkett (qv), brother of Patrick, was envoy of the catholic Confederation to the pope in 1648. Oliver Plunkett stayed in the Irish College, Via degli Ibernesi, Rome, from 1650 to 1654 (or perhaps 1656) and studied at the Jesuit university, Il Collegio Romano, and later at the Collegio di Propaganda Fide. He received tonsure and minor orders in the basilica of St John Lateran on 4 March 1651, and sub-diaconate there on 20 December 1653, and was ordained deacon in the chapel of Propaganda Fide College on 26 December 1653, and priest on 1 January 1654 by Anthony MacGeoghegan (qv), OFM, bishop of Clonmacnoise. After his petition of 14 June 1654 to stay in Rome, he was exempted from his student oath to return immediately on mission to Ireland. He studied law for three years at Sapienza University, and was appointed (November 1657) professor of theology in the Collegio di Propaganda Fide. A man of culture and books, he was nominated consultor of the Sacred Congregation of the Index. In his twelve years as professor he resided with the Oratorian Fathers in San Gerolamo della Carità and assisted as chaplain in the nearby hospital of Santo Spirito. Agent in Rome for Patrick Plunkett, bishop of Meath, from 1669 he was nominated agent for the province of Dublin by Peter Talbot (qv), archbishop of Dublin.
Plunkett petitioned successfully for the see of Armagh, vacant after the death of Edmund O'Reilly (qv) in 1669. Pope Clement IX favoured his appointment, though the agent of the Armagh clergy had petitioned that no Meathman should be appointed; the cleavage between Old Irish and Anglo-Irish was still wide after the bitter divisions of the confederate war. Plunkett was ordained bishop on 1 December 1669 by Bishop D'Allamont of Ghent in the private chapel of the episcopal residence. In London he received an audience with the queen, Catherine of Braganza.
He arrived in his diocese in March 1670, and on the whole was warmly welcomed. His active episcopacy lasted nine years and nine months. Ireland was still suffering from the effects of the Cromwellian decade. Lodged near Dundalk with Sylvester MacMahon (Matthews), he held a synod for the Louth clergy in Dunleer and for the northern clergy in Blyke's Inn, Dorsey, Co. Armagh. He confirmed some 10,000 people, young and old, in his province, and founded two schools for the education of boys and the training of priests under the directorship of Jesuit fathers and of diocesan priest Edward Drumgoole, first in the Dundalk area and in 1672 in Drogheda; an educated and disciplined clergy was one of his main pastoral desires. The Drogheda schools were suppressed in November 1673. Among the priests who assisted him greatly in his diocese were Drumgoole, Dean Brian MacGurk (qv), and Henry Hughes, his vicar-general. He ordained some 200 priests in Ireland, some at Ballybarrack, Dundalk. Though of Anglo-Irish background, he had a sympathy for the Ulster Gaelic nobility who had lost their property. With the approval of the lord lieutenant, Lord Berkeley (qv), he met a large group of Tyrone tories in September 1670 and arranged pardons and a safe conduct for fifteen of them to go abroad.
On 17 June 1670 he convened in Dublin an assembly of the bishops of Ireland (the four archbishops, with Patrick Plunkett of Meath, and James Phelan (qv) of Ossory) to arrange the appointment of more bishops. They passed ten statutes on pastoral matters, in particular limiting the rights of religious orders to questing, and presented to Berkeley (a catholic sympathiser) a modest address of loyalty to the king in civil affairs. Plunkett's friendly relationship with Berkeley, Henry Moore (1st earl of Drogheda), Archbishop James Margetson (qv) of Armagh, and the 1st Viscount Charlemont (qv), helped him to pursue his pastoral work discreetly. He convened a provincial council of his suffragan bishops and of the superiors of the Franciscan and Dominican orders in Clones (August 1670), which in twenty-eight decrees laid down laws for the discipline of the clergy and proper conduct of the laity, and removed from office the scandalous Terence O'Kelly, vicar-apostolic of Derry. The archbishop made a pastoral visitation of six dioceses, and visited Dunluce to consult the 1st marquess of Antrim (qv) about a mission to the Hebrides.
Plunkett's friend John Brenan (qv), bishop of Waterford and later archbishop of Cashel, described him as touchy and hot-tempered. His pursuit of Roman discipline sometimes went against the grain of the native way, and this (combined with his conscientious zeal) caused resentment among clergy with tory connections whom he had disciplined. Some of the Franciscans, after their houses had been dissolved, acted as curates in the larger rural parishes of Tyrone and Armagh. In 1671 he went to Counties Down, Fermanagh, and Louth to consult on the dispute between the Dominicans and the Franciscans concerning the rights of questing in four northern dioceses. The Franciscans and their lay friends were openly hostile to him when he decided uncompromisingly in favour of the Dominicans.
In 1671 he visited the dioceses of Armagh and Raphoe and the sick Bishop Patrick Plunkett in Dublin; installed new vicars of Derry and Dromore; welcomed Brenan, who had arrived in Dublin from Rome; and consecrated the bishop of Clonfert, Thady Keogh, OP. In 1672 he paid a seven weeks visit to Dublin. He reconciled to the church the Franciscan friar Thomas Harold (a former adherent to the pro-government ‘remonstrance’ of the 1660s), and saw to his safe departure abroad. He and Archbishop Talbot engaged in an unseemly dispute on the primatial rights of Armagh and Dublin. Plunkett maintained that his primacy gave him a jurisdiction over all Ireland; he played an active part in solving disputes in various dioceses and reported on them to Rome. His short book in English, Jus primatiale (Dublin, 1672), a defence of Armagh's primacy, was answered by Talbot in his book in Latin, Primatus Dublinensis (Lille, 1674). The archbishops were reconciled in 1672 by Bishop John O'Molony (qv) of Killaloe. Plunkett held a diocesan synod in May 1672; installed vicar-apostolic Gerard Farrell in Ardagh; met the new viceroy, the earl of Essex (qv), in August; saw to the replacement of vicar Patrick McColyn in Clogher; and attended the Franciscan provincial chapter at Elphin (November).
In the spring of 1673 he spent six weeks in Connacht. Resentment in the English parliament at the king's tolerance of catholics (in the declaration of indulgence) caused a wave of persecution. On 8 May he attended, as a defence witness, a meeting of a government commission enquiring into Archbishop Talbot's conduct. Talbot was banished; bishops and priests went underground after the edict of expulsion from Ireland of all priests and religious (27 October 1673). Plunkett and Brenan found refuge for some six months in south Armagh, where they suffered severe privations. In the summer of 1674 Plunkett reported to Rome a famine in which 400 catholics in his diocese died of hunger. In 1675 he wrote to Rome discouraging the appointment of more bishops; new bishops, however, were appointed in 1676 to Kildare, Clogher, Cork, and Cloyne. Fr Michael Plunkett (qv), his secretary and relative, went to study in the Irish College, Rome, and for a while acted as clergy agent in Rome. Archbishop Plunkett visited his friend Brenan and relatives in Munster and south Leinster in the autumn. He was involved in the dispute between some clergy and Thomas Fitzsimons, vicar general of Kilmore, which continued to 1678; his decision against Fitzsimons was later confirmed by Rome. He reported to Rome on the religious situation in Cashel and Waterford dioceses.
The archbishop held synods of his own clergy every two years and finally a provincial synod at Ardpatrick, near Louth village (28 August 1678), which issued twenty-six decrees directed at the sanctification of the faithful, the ending of clerical scandals, and restoration of church discipline. A commission was set up to study problems regarding the rights of heads of religious orders, conventual discipline, and questing for alms. He visited the diocese of Clonmacnoise.
After the alleged discovery of a ‘popish plot’ in 1678 the bishops went into hiding again. In October 1679 Plunkett risked a visit to Dublin to Bishop Plunkett of Meath, who was ill and who died on 18 November. On 21 October 1679 the English privy council instructed the lord lieutenant, the duke of Ormond (qv), to arrest Plunkett and Bishop Patrick Tyrrell (qv) of Clogher. A letter had been given to the duke of York (qv) in Brussels accusing Col. John Fitzpatrick (qv) (Plunkett's benefactor, and brother-in-law of Ormond) and the two bishops of plotting to bring a French army to Ireland. Plunkett was arrested on 6 December in Dublin, imprisoned in Dublin castle, and tried in Dundalk (23 July 1680) on two bills of indictment, one for treason and one for exercising papal jurisdiction. When Edmund Murphy (qv), a priest whom he had suspended, failed to appear as a witness, the trial broke down. But on 6 October Plunkett was sent for trial to London and was transferred to Newgate prison. In April 1681 the Westminster grand jury found a true bill against him and returned him for trial. On 3 May he was arraigned for high treason before the king's bench and given five weeks to bring his witnesses from Ireland. On 8 June, before their arrival, he was tried for high treason and found guilty on perjured evidence. Lay and priest witnesses, including Florence MacMoyer (qv) and the hostile friar John MacMoyer (qv), were weak and unimpressive. Beyond protesting against being tried in England, the archbishop made little defence. In prison he was attended by his servant and friend for eleven years, James MacKenna, and by Dom Maurus Corker OSB, a fellow-prisoner. His last speech was printed in London. His courage, forbearance, and forgiving attitude during his imprisonment revealed his saintly nature. He was executed at Tyburn on 11 July 1681. It was probably during his imprisonment that Garret Morphy (qv), a Dublin portraitist, drew the sketch on which later paintings of him are based.
Plunkett was beatified by Benedict XV (23 May 1920) and canonised by Paul VI (12 October 1975). His relics are venerated in St Peter's church, Drogheda (where his head is kept), Downside Abbey, England, and Lampsringe, Germany.