Burgh, William de (1312–33), 3rd earlof Ulster , lieutenant of Ireland, was born in 1312, the eldest son of John de Burgh (d. 1313) and Elizabeth de Clare (qv), sister of Gilbert de Clare, earl of Gloucester. His uncle Edmund de Burgh (qv) and his cousin Walter de Burgh (qv) were appointed guardians of the Irish lands of his grandfather, Richard de Burgh (qv), after his death in 1326. Despite his minority William was granted his English lands on 3 February 1327 and his Irish lands (together with the title earl of Ulster) two days later (though on 10 October that year the custody of Carrickfergus castle was placed in the hands of the Irish administration and it was not returned until the following May). The favour that resulted in de Burgh's early assumption of his inheritance was the result of his mother's connections with the English court and the influence of Henry, earl of Lancaster and of Leicester, into whose wardship he had been placed. As heir to his mother, who held a third of the Gloucester lands in England, Wales, and Ireland, William was a major player on the English as well as the Irish stage. He married Maud, daughter of Henry and Maud de Chaworth, around May 1327; they had one child, Elizabeth de Burgh (qv) (d. 1363).
Early in 1327 a letter came from his mother's (Elizabeth de Clare's) attorney in Ireland, pleading that William be knighted without delay and sent to Ireland with military backing to prevent the disintegration of his earldom, as members of his family were usurping his rights and refusing to obey mandates. Later in the same year a number of his less recalcitrant kinsmen visited him in England and proffered their loyalty. He was summoned to parliament in December 1327. On 22 May 1328 he was knighted by Edward III in London and he was present at the royal wedding between David Bruce (later David II, king of Scots) and the king's sister Joan at Berwick, following the treaty of Northampton. Shortly afterwards, to allay the concerns of those in Ireland who clamoured for his return, he was accompanied to his earldom by King Robert of Scotland. He attended parliament at Dublin on 15 August and then set out to view his lands in Connacht.
Over the next two years he came into conflict with Maurice fitz Thomas FitzGerald (qv), partially as a result of continuing Geraldine–de Burgh friction and contention over the disputed lands of the Clare legacy in Munster and Thomond. He attended the two parliaments held at Dublin in January and April 1329. At the former he was one of those Anglo-Irish lords who backed legislation to force the leaders of great lineages to censure their more unruly followers. Violence broke out in July 1329 when he marched against Brian Bán O'Brien (qv), fitz Thomas's ally; he was defeated at Thurles. In July the following year, after a parliament at Kilkenny, he accompanied the army of the justiciar (Roger Outlaw (qv)) to campaign against O'Brien, and, though the force did little before breaking up, a contingent led by Walter de Burgh raided fitz Thomas's lands. At the parliament at Kilkenny in August, fitz Thomas, now earl of Desmond, was accused of aiding O'Brien, and was arrested and imprisoned; to forestall future conflict William was placed in the custody of the king's marshal at Limerick. He was released shortly afterwards, following Desmond's escape from captivity.
By spring 1331 de Burgh was back in England and on 3 March he was appointed the king's lieutenant. There was now no doubt where Edward III's sympathies in Ireland lay. De Burgh's appointment as lieutenant was to complement the activities of the new justiciar, Anthony Lucy (qv). His responsibility was peacekeeping, primarily in Ulster and Connacht; he had little involvement in running the administration and was to act on the advice of the justiciar and the Irish council. Now armed with new authority, in September he ordered the arrest of Henry de Mandeville (qv), the former seneschal of Ulster, who had actively resisted his overlord's authority, and in November Walter de Burgh was captured on the earl's orders. Though the cousins had cooperated initially, their interests had diverged after the summer of 1330, when Walter's attempt at independent self-aggrandisement in Connacht contradicted the earl's policy of cooperation with Toirrdelbach O'Connor (qv).
Relinquishing his lieutenancy, William was summoned to England on 5 November 1331 to advise the king on a proposed expedition to Ireland. By May 1332 he had returned to Ireland, where he acted as one of the guarantors for the earl of Desmond when he was released from another term in prison. Early in 1333 he was involved in preparing an expedition to Scotland but on 6 June he was murdered near Carrickfergus by John Logan and members of the Mandeville family, at the instigation, it is said, of Jill de Burgh, sister of Walter, who had died, probably of starvation, in Northburgh castle in 1332. After William's death his wife and daughter fled from Ulster to England.