John Forbes (5 September 1707 – 11 March 1759) served in the British Army during the French and Indian War. In 1758, he commanded an expedition, with Lieutenant-Colonel George Washington leading a provincial militia, that occupied the French outpost of Fort Duquesne, now Pittsburgh, Pennsylvania. He oversaw the construction of a military trail known as the Forbes Road, which became an important route for settlement of the Western United States.

John was the youngest child of John Forbes (1658–1707), sixth son of the John Forbes, 2nd Lord Culloden, and Elizabeth Graham, daughter of an Edinburgh merchant. His cousin was Duncan Forbes (1685 –1747), 5th Lord Culloden and Lord President of the Court of Sessions. In 1707, the younger John was born at Pittencrieff House, near Dunfermline, which his father had purchased in 1701. John the elder was Lieut.-Colonel and Brigadier, Maitland's Regiment, and died several months before his son’s birth.

Forbes grew up at Pittencrieff House and probably studied medicine at Edinburgh University. In 1729, he was appointed surgeon in the Royal Scots Greys and in 1735 he was commissioned as a cornet, the modern equivalent of a second lieutenant. Due to his relative poverty and the British commission purchase system, Forbes was not promoted to lieutenant until 1742. He was posted to the Austrian Netherlands to fight in the War of the Austrian Succession at Dettingen in June 1743. He purchased a commission as captain in 1744 and his commission as Lieutenant-Colonel of the Scots Greys in 1750. He saw service in the suppression of the 1745 Jacobite uprising, including the Battle of Culloden on his cousin Duncan Forbes’s estate.

The territorial disputes between British and French colonies in North America led to the 1754-1763 French and Indian War. In 1757, Forbes was promoted colonel of the 17th Foot, part of a force of 5,400 sent to Novia Scotia. Forbes was promoted Brigadier general in 1757 and given command of an attack on the French stronghold Fort Duquesne. Among his combined forces were 5,000 provincial militia from Virginia and Pennsylvania, commanded by 26-year-old Colonel George Washington. Part of his orders included expanding a trail cut through the Allegheny Mountains in order to support additional troops. From his base at Carlisle, Pennsylvania, Forbes constructed a road through Fort Loudon, Cowans Gap, Raystown Camp (later called Fort Bedford), and Loyalhanna Post (later called Fort Ligonier.)

On November 24, 1758, Forbes’s vanguard of mortars and howitzers was twelve miles from Fort Duquesne. That evening, Indian scouts reported "a very thick smoke from the front extending in the bottom along the Ohio." A remarkable message soon arrived: "the enemies had abandoned their fort after having burned everything." Philadelphia's Pennsylvania Gazette featured headline new from the front: "I have the pleasure to write this letter upon the spot when: Ft. Duquesne once stood while the British Flag flies over the debris of its bastions in triumph. Blessed be to God, the long looked for day is arrived."

On that site, Forbes ordered the construction of Fort Pitt, named after British Secretary of State Pitt the Elder. He wrote to Pitt: "I have used the freedom of giving your name to Fort Duquesne, as I hope it was in some measure actuated by your spirits that now makes us masters of the place." He also established a settlement between the rivers, the site of modern Pittsburgh. On 3 December 1758, he returned to Philadelphia, where he died on 11 March 1759. He was buried in the chancel of Christ Church, Philadelphia. His final correspondence with Lord Amherst, the new commander in North America, included the recommendation he make his relationship with Native Americans a priority and “not to think lightly of them or their friendship.”

By fortifying his road, General Forbes intended it to be defensible against Indian and Canadian raiding parties and the raids attempted the following winter all failed. The “Forbes Trail” became an enduring route to the Ohio country from Pennsylvania. The citizens of Pittsburgh honored his memory with Forbes Avenue from downtown Pittsburgh to Frick Park and with Forbes Field, the home field for the Pittsburgh Pirates, Pittsburgh Steelers and the Pitt Panthers football team.