Bourke, William (1623–67), 5th Baron Castleconnell , soldier, was son and heir of Edmund Bourke and his first wife, Thomasine, daughter of Sir Thomas Browne of Hospital, Co. Limerick. Edmund held over 3,000 acres in Co. Limerick, primarily in the barony of Clanwilliam, alongside the Shannon river, and a further 1,000 acres in Co. Tipperary. William was raised a protestant and matriculated at Trinity College Dublin in 1638, the year his father died. He reverted to catholicism shortly afterwards, and together with his kinsman, Theobald Bourke, Lord Brittas, was one of the first lords to join the rebellion in late 1641. Despite his youth, Castleconnell commanded a regiment of the confederate Munster army that captured Limerick castle in June 1642, and was defeated by the royalist Murrough O'Brien (qv), Lord Inchiquin, at Liscarroll, Co. Cork, two months later. Castleconnell attended the general assemblies in Kilkenny on a number of occasions, but his primary involvement was in the military sphere. He served under James Tuchet (qv), 3rd earl of Castlehaven, when his regiment took part in the Ulster campaign of 1644. The following year, during a major confederate offensive in Munster, Castleconnell captured six castles and laid siege to the city of Limerick, which had adopted a policy of strict neutrality. The general assembly subsequently dismissed a complaint by the city authorities against Castleconnell for his conduct at this time.
In the early days of the war, he married Ellen, daughter of Maurice Roche (qv), 3rd viscount Fermoy, and loyally supported Fermoy against his confederate rivals, Richard Butler (qv), 3rd Viscount Mountgarret, and Donough MacCarthy (qv), 2nd Viscount Muskerry. In 1646 Muskerry and Mountgarret led the faction at Kilkenny that signed a peace treaty with the royalist lord lieutenant James Butler (qv), marquess of Ormond. Castleconnell, along with Fermoy and Brittas, sided with the papal nuncio, GianBattista Rinuccini (qv) in opposing this move, seizing control of confederate government in the process. The three Munster lords also successfully nominated Edward Somerset (qv), earl of Glamorgan (an ardent nuncioist), as commander in Munster, although the provincial army soon began to disintegrate as factional struggles intensified. By October 1648, however, as the confederate military situation deteriorated, Castleconnell switched sides and attended the general assembly in defiance of Rinuccini. After the second Ormond peace treaty (January 1649), Castleconnell fought in the royalist army against the Cromwellians, and was elected by the gentry of Tipperary to command the troops raised in that county. By October 1651, believing that further resistance was futile, he helped organise the surrender of Limerick to the parliamentarians, despite the opposition of the city's military commander, Hugh O'Neill (qv).
Although his family agreed to be transplanted to Connacht, Castleconnell (outlawed in 1643) fled abroad and served as a pikeman in the regiment of James, duke of York (qv). After his return to Ireland in 1660, he sought to recover his estates, and was named in the act of settlement (1662) after the direct intervention of Charles II. The decree of restitution was never enforced, however, and he received a temporary annuity of £1,000 instead. Treasury officials successfully defrauded him of this, and he died in relative poverty shortly after April 1667. Castleconnell was succeeded by his son Thomas, while his grandson William sat in the Jacobite parliament of 1689, and followed James II into exile, forfeiting the peerage as a result.