Burgh (Boroughs), Thomas (d. 1597), 5th Baron Burgh of Gainsborough , lord deputy of Ireland, was the second but eldest surviving son of William, 4th Baron Burgh, and his wife, Katharine, daughter of Edward Clinton, earl of Lincoln. Having embarked on a military career, he served as governor of the town of Brill, Flanders, from 1587 until his death. He was nominated a Knight of the Order of the Garter on 23 April 1593, being installed on 25 June. That same year he was sent as an ambassador to the court of King James VI of Scotland. In January 1596 he was granted leave to return to England from Flanders on account of ill health.
As early as September 1596 Burgh was being considered for the lord deputyship of Ireland, but his appointment was delayed first by politicking at court and then by protracted haggling with the queen over his powers and pay. He was appointed lord deputy 5 March 1597, and on 8 April provision of £1,200 was made for his costs of transportation to Ireland. The queen also agreed that he could retain his governorship of Brill. However, he learned to his dismay that the queen had withheld from him the customary power to grant knighthoods. He landed in Dublin on 15 May, was sworn lord deputy on 22 May, and set about restoring the morale and discipline of both the royal administration and the army.
A confederation of Gaelic lords headed by Hugh O'Neill (qv), earl of Tyrone, held the province of Ulster in open rebellion, but the rest of the island was relatively quiet albeit increasingly unsettled. Following two years of fruitless negotiating and little military activity, Burgh was determined to seize the military initiative. Starved of men and resources because of the queen's parsimony, he recruited Irish soldiers on an unprecedented scale. His army of 3,500 was composed mainly of untrained and unreliable local troops, with a small nucleus of professional English soldiers and enthusiastic English gentleman volunteers. He left Dublin on 5 July, planning to march through the heart of Ulster to Lifford, where he would meet up with a force marching from Connacht, led by Sir Conyers Clifford (qv).
After supplying Armagh, on 13/14 July Burgh reached the Blackwater river, where the ford was defended by a high bank and deep ditch manned by forty rebels. He ordered an attack and, when his men wavered, led the way across the river. Taken unawares, the defenders fled. O'Neill was nearby with his main army and attempted a surprise attack the next day, but his forces were beaten back. However, some of Burgh's men, ignoring his earlier warning not to leave themselves open to an ambush, followed the rebels into the woods and in unfavorable terrain suffered heavy casualties amid fierce hand-to-hand fighting. Among the dead were several officers and Burgh's son-in-law, which encouraged O'Neill to claim a victory. Despite this, the queen was impressed and relaxed her prohibition against the dubbing of knights, although she did gently chide Burgh for putting his own life in danger.
Burgh began building a fort on the Blackwater and opened negotiations with O'Neill. It soon became apparent that O'Neill was playing for time and, having completed the fort, Burgh angrily broke off talks on 10 August. Running low on supplies and concerned by both his own troops’ inexperience and by the strength of the rebels’ resistance, he returned to Dublin. He also ordered Clifford to withdraw, but the rebels intercepted this letter. As a result, Clifford's army became isolated in west Ulster, suffered heavy losses, and was fortunate to fight its way back into Connacht. This was a serious strategic reverse, but Burgh remained optimistic.
In early October Burgh returned with his army and, after a fierce skirmish with the rebels, relieved the Blackwater fort. He planned on marching to Lough Foyle and establishing a garrison there, despite concerns of his advisers that he did not have enough men. However, on the march north he had fallen ill with typhus and his condition deteriorated rapidly. He was carried back to Newry, where he died 13 October 1597. Burgh's strategy of constantly harassing the rebels by campaigning throughout the year and of surrounding the rebel heartland with a network of royal forts was fundamentally sound, but he lacked the resources to execute it. In practice, the need to supply isolated forts left the royal armies vulnerable to ambush. Nonetheless, the royal cause could ill afford the loss of a commander of Burgh's vigour and experience.
Burgh's lands at Gainsborough, Lincolnshire, were mortgaged to the value of £2,491 at the time of his death. He married Frances (d. 1647), only daughter of John Vaughan of Sutton-on-Derwent, Yorkshire, with whom he had one son, Robert, who died as an infant 26 February 1602, and four daughters – Elizabeth, Anne, Frances, and Katherine. He was buried in Westminster in January 1598.