MONTRESOR, JOHN. (1736–1799). British military engineer. Born at Gibraltar, the son of James Gabriel Montresor, John Montresor went to America ahead of his father in 1754 and, appointed an additional engineer by Edward Braddock, was wounded at the Monongahela on (9 July 1755). He then served on the New York frontier and took part in the earl of Loudoun's so-called Cabbage Planting Expedition to Halifax, Nova Scotia, in 1757. He served under Jeffrey Amherst at the capture of Louisburg (1758), James Wolfe at the siege of Quebec (1759), and James Murray in the final conquest of Canada in 1760. During most of this time he specialized in scouting missions and dispatch carrying. In 1761 he explored the route up the Kennebec River in Maine that was later used by Benedict Arnold in his march to Quebec.
At the start of Pontiac's uprising, Lieutenant Montresor was sent from New York City with letters for the commander at Detroit. Delayed at Niagara for almost a month awaiting passage, he sailed on 26 August 1763 with provisions and a seventeen-man detachment of the Seventeenth Regiment commanded by Captain Edward Hope. Shipwrecked two days later, Montresor fortified the temporary camp and enabled the survivors and a one-hundred-man reinforcement that arrived on 2 September to beat off Indian attacks that lasted from dawn to dusk on 3 September. Finally reaching Detroit, he stayed there until 20 November 1763, when he left with Robert Rogers (the famous ranger) and a large detachment to return to Niagara. The next year he fortified the portage at the latter place and went with John Bradstreet to Detroit, where he improved the defenses.
He returned from England in 1766 as a captain lieutenant and barrackmaster. During the next few years he worked on fortifications or barracks at New York City, Boston, Philadelphia, and the Bahamas. Montresor surveyed the boundary line between New York and New Jersey in 1769, and in 1772 he bought what was later called Randall's Island in the East River and lived there with his wife and family.
Montresor saw considerable service during the first three years of the War of American Independence. He was present at Lexington and Concord (19 April 1775) and laid out a redoubt on Bunker Hill to cover the retreat of the British to Boston that General Thomas Gage ordered abandoned later that day. He fought in the Battle of Bunker Hill on 17 June to regain the position Gage had let slip away two months earlier. Montresor was appointed chief engineer in America on 10 December 1775 and promoted to captain on 10 January 1776. He blew up Castle William, at the mouth of Boston harbor, when the British evacuated in March. He served as an aide to William Howe at the Battle of Long Island (27 August 1776), directed the artillery at the Battle of Brandywine (11 September 1777), and was present at the Battle of Germantown (4 October 1777). He supervised the construction of the British defenses around Philadelphia in the fall of 1777 and directed the attack on the Delaware River forts. (He had begun the fort on Mud Island, renamed Fort Mifflin, in 1771.) He organized the Mischianza, an elaborate entertainment held on 18 May 1778 at Philadelphia to honor Howe on the eve of his return to Britain. He fought under Sir Henry Clinton, Howe's successor, at Monmouth (28 June 1778), but his ties to Howe seem to have incurred him the displeasure of Clinton, who praised James Moncrieff as "an engineer who understood his business" but did not mention John Montresor once in his memoirs. Montresor returned to England later that year and retired from the army. He died in debtor's prison at Maidstone on 26 June 1799
Skull, G. D., ed. The Montresor Journals. New York: New-York Historical Society, 1882.
revised by Harold E. Selesky