General John Campbell, 4th Earl of Loudoun (5 May 1705 – 27 April 1782) was a British nobleman and army officer. In 1756, Loudoun was sent to North America as Commander-in-Chief and Governor General of Virginia, where he was unpopular with many of the colonial leaders. When he learned that some merchants were still trading with the French, while he was trying to fight a war against them, he temporarily closed all American ports. Despite his unpopularity the county of Loudoun, formed from Fairfax in 1757, was named in his honour.[1] As Commander-in-Chief during the Seven Years' War (called the French and Indian War in the Thirteen Colonies), he planned an expedition to seize Louisbourg from the French in 1757 but called it off when intelligence (possibly including a French military deception) indicated that the French forces there were too strong for him to defeat. While Loudoun was thus engaged in Canada, French forces captured Fort William Henry from the British, and Loudoun was replaced by James Abercrombie and returned to London. Francis Parkman, a 19th-century historian of the Seven Years' War, rates his martial conduct of the affair poorly.

Many historians debate whether he played a fundamental part in the Seven Years' War. Arguably, he was an influential figure as he embarked on reforms for the army such as replacing the ordinary musket with the flintlock musket for greater accuracy. He made improvements by embarking on a road improvement programme, recognising the need to supply the army as he replaced the traditional supply line with army wagons. His focus was centralising the system of supplies and had built storehouses in Halifax and Albany, whilst recognising the importance of waterways as a means of transport. Most notably, he integrated regular troops with local militias-and the irregulars were to fight a different kind of war, than the linear, European style of warfare in which the British had previously been trained.