Carleton, Sir Guy (1724–1808), 1st Baron Dorchester , soldier, and colonial governor, was born 3 September 1724 in Strabane, Co. Tyrone, third son of Christopher Carleton of Newry and his wife Catherine (née Ball) from Co. Donegal. He had three brothers and three sisters. Guy Carleton was a descendent of Lancelot Carleton, a soldier from Cumberland who settled in Enniskillen in the early seventeenth century. Christopher Carleton died when Guy was about fourteen years old, and his mother soon married the Rev. Thomas Skelton of Newry, a Church of Ireland rector, who is regarded as having seen to Carleton's education. In 1742, at age seventeen, Carleton was commissioned an ensign in the Earl of Rothes’ regiment, the 25th Foot, and was promoted lieutenant in 1745. Carleton changed to the 1st Foot Guards on 22 July 1751 and was made captain-lieutenant and lieutenant-colonel on 18 June 1757. During the Seven Years War, in the summer of 1758, he served at the siege of Louisbourg in Nova Scotia, and was promoted lieutenant-colonel in the 72nd Foot. Carleton was brought on to the staff of Gen. James Wolfe, over the objections of George II, as quartermaster-general and engineer, and was promoted colonel on 30 December 1758. He participated in the capture of Quebec (September 1759), where he was wounded. He also saw action at Port-Andro, on Belle-Île-en-Mer on the French coast (8 April 1761), and at the siege of Havana in Cuba (22 July 1762). Carleton was made lieutenant-governor of Quebec in 1766, and in the absence of the governor, he assumed administrative responsibility for the province the following year. In 1770 he returned to England on a leave of absence, during which time he was promoted major-general, was consulted by a parliamentary committee in drafting the Quebec act of 1774, and on 3 January 1775 was appointed governor of Quebec. Carleton was a success. He appointed French-Canadian Roman Catholics to his legislative council and numerous other positions within the province, reestablished French civil law, and, under the Quebec act, allowed the catholic church to continue its public functions. Indeed, Carleton allied himself with the catholic clergy.
With the outbreak of hostilities in the thirteen colonies in 1775 the forces of the continental congress invaded Quebec, driving British troops from Montreal to Quebec city; Carleton narrowly avoided capture. Quebec was besieged for six months, but held, giving Carleton the title of ‘savior of Quebec’. In the spring British reinforcements by sea lifted the siege, although Carleton was unable to capture the retreating American army. Though criticised for this failure, Carleton was promoted lieutenant-general on 1 January 1776, made a knight of the Order of the Bath on 6 July 1776, and later granted the government of Charlemont by the king as a sinecure. Carleton's subordinate, Maj.-gen. John Burgoyne, commanded the expedition defeated at Saratoga. Carleton resigned in protest, returning to England in June 1778. On 2 March 1782 Carleton succeeded Sir Henry Clinton as commander-in-chief of British forces in North America. He had instructions to negotiate peace with the colonies, but Carleton's real task was to extract the remaining 30,000 British troops and 27,000 loyalist refugees from the northern states. He also arranged land grants for many of the loyalists settled in Nova Scotia and Quebec. Carleton sailed from New York for England in December 1783.
Carleton was appointed governor of Quebec, Nova Scotia, New Brunswick, and Newfoundland on 11 April 1786, and on 21 August he was created 1st Baron Dorchester and voted a pension of £1,000 a year. He continued to work closely with the catholic clergy, e.g. by giving an official voice to the selection of bishops and admitting priests from France, although he had become disillusioned with the lack of support from French Canadians during the American war. He was more supportive of the British merchants and the loyalists from America. The outbreak of war between Britain and France in 1793 complicated Dorchester's mission. Seven forts, clearly within the territory ceded to the United States, had been retained by the British in order to support both fur traders and Native people. As skirmishing rose in intensity between Native people and Americans, Dorchester built a new fort well into American territory in 1793 and assured the Native people on 10 February 1794 that war within the year was likely. This caused alarm in the United States. The government intended to settle with the Americans because of the war with France, and Dorchester was admonished by the government. Indignant, Dorchester asked to be relieved of his duties on 4 September 1794. While the government preferred that Dorchester remain at his post, by 9 July 1796 he was replaced and sailed for England.
On 12 August 1793 he had been promoted a general in the army, and back in England he moved from the 15th to the 27th Dragoons and finally to the 4th Dragoons. Dorchester had married (22 May 1772) Lady Maria, daughter of Thomas, 2nd earl of Effingham. They had nine sons and two daughters. He acquired three residences in England, Greywell Hill, Basingstoke, Kempshot House, Basingstoke, and Stubbings House, near Maidenhead. He died at Maidenhead on 10 November 1808. Dorchester's younger brother, Thomas Carleton (born 1735, probably in Strabane), was a soldier and lieutenant-governor of New Brunswick from 1784 to 1817. Dorchester's private papers were destroyed; official correspondence can be found in the War Office and Colonial Office collections of the National Archives (Kew).