Dease, Thomas (Déis, Tomás) (c. 1568–1651/2), catholic bishop of Meath and poet in Irish, was second of three sons of Richard Dease of Turbotstown, Co. Westmeath, and his wife Lady Eleanor Nugent of Carlanstown, Co. Meath. He was closely related to the Nugents of Delvin and many of the other noble families of the Pale. In later years, on the death of his older brother James, Thomas inherited his family's estates. After receiving some education at home (including a grounding in Latin and possibly in Irish letters) he undertook clerical studies at the Irish college in Douai and later in Paris, where he received a doctorate in philosophy, theology, and canon law at the Sorbonne. In 1612 he became professor of theology in the College of Navarre, before being appointed president of the Irish college in Paris (which he helped to found). He returned to Ireland (October 1622) after being secretly installed as bishop of Meath in Paris in May of that year.
Closely aligned with the Old English faction in the divided Irish church, he instinctively sought accommodation rather than confrontation with the Dublin administration. His training in the largely Old English and Tridentine colleges at Douai and Paris was bound to bring him into conflict with the Old Irish clergy, who tended to gravitate towards colleges in areas of Spanish influence and whose political leanings were in stark contrast to his own. In his new office, he quickly established himself as a leading partisan of the Old English faction within the church. One of his first actions was to expel many of the politically suspect Ulster priests who had previously been encouraged to settle in the diocese; this later militated against the success of his candidature for the see of Armagh (1625–6). He engaged in a largely successful power struggle with religious orders who were seeking to regain within his diocese the ecclesiastical jurisdiction and land (usually now occupied by Old English landholders) they had lost at the time of the reformation. One of his tactics in this war of attrition was to use his influence on the Continent to secure the appointment of his own followers to defunct benefices that orders such as the Cistercians and the Augustinians were seeking to have restored to them. His encouragement of newer, post-Tridentine orders (notably the Jesuits and the Capuchins) to become active within his diocese may also have been part of this campaign.
He is of historical significance mainly because of the stance he adopted during the war of the 1640s. When fighting began in 1641, he urged his flock to take no part in it, and was loud in his condemnation, on both moral and practical grounds, of the rebels’ efforts, which he saw as having no hope of success. He would appear to have been influential in preventing Richard Nugent (qv), earl of Westmeath, in whose house he reportedly lived (1622–42), from taking part in the conflict in its early years. He was conspicuously absent from a synod held at Kells (March 1642) by the ecclesiastics of the Armagh province, which supported the insurgents, excommunicated all recalcitrant catholics within its remit, and (to little practical effect) suspended Dease from his duties. Later on (probably in autumn 1643) he switched sides and joined forces with the confederation of Kilkenny. It is not clear what made him change his mind; however, he may have been influenced by the backing of the papal envoy Scarampi (qv) – who arrived in Ireland in June 1643 – for the confederation. In any case, he never wholeheartedly supported the war effort, and came repeatedly into conflict with those who did, particularly after the signing of the March 1646 peace with Ormond (qv). He was a leading member of the faction opposed to the papal nuncio Rinuccini (qv) and, along with the rest of what remained of the supreme council, was subsequently excommunicated a second time for his troubles. Since he was an old man in the 1640s, his vicar general and nephew Oliver Dease (d. 1674) is often found acting as his faithful proxy during these years.
When Cromwell arrived in Ireland in 1649, Thomas Dease went to Galway city, where he died in 1651/2, before the city surrendered, and was buried under the threshold of the sacristy of the church of St Nicholas. His policies both before and after the outbreak of hostilities show remarkable consistency in that he may, at all times, be seen as a politically conservative, Old English, Tridentine catholic, seeking accommodation rather than conflict with the Dublin administration, and attempting to serve the best interests of the country as he saw them. Although he is defended by Lynch in De praesulibus Hiberniae (pp 167–71), he was seen as a heretic and a wrecker by the authors of Commentarius Rinuccinianus (see, for example, iii, 288), and he comes in for particular vilification in An aphorismical discovery of treasonable faction (Gilbert, i, pt 1, 278), whose anonymous author sees him as a sectarian rebel more given to enjoying life and composing libellous verse of little artistic value than to serving his flock or his country. Although this assessment of Dease's poetic skills is politically motivated and unfair, his poems are those of a gifted amateur rather than a professionally trained poet (despite Lynch's claims to the contrary in De praesulibus, 169–70). The six surviving compositions attributed to him are in loose syllabic metre; they are mainly of a religious or morally didactic nature, and are generally ironic or disdainful in tone. These are ‘Mór sochair na haimsire’ (ed. Ó Tuathail, 1953), ‘Rinneas [MS Roinneas] mo thiomna, a Shéamuis’ (ed. Ó Tuathail, 1955), ‘Gabh mo theagasg, a inghean óg’ (ed. Ua Brádaigh), ‘A dhuine ó ndeachaidh do bhean’ (ibid.), ‘Is fada m'ocht, a Shéamuis’ (TCD, MS H.5.2), and a single quatrain, ‘As mór deimhniughadh na gcompánach’ (ed. Ua Brádaigh).