The regiment was raised in Stirling by Colonel George Perry as the 57th Regiment of Foot in 1755 for service in the Seven Years' War. It was re-ranked as the 55th Regiment of Foot, following the disbandment of the existing 50th and 51st regiments, in 1756. The regiment embarked for North America for service in the French and Indian War and arrived in Nova Scotia on 8 July 1757 with the objective of taking part in the abandoned attack on the Fortress of Louisbourg. The regiment returned to North America for the American Revolutionary War. The regiment fought at the Battle of Long Island in August 1776 and the Battle of Princeton in January 1777. It went on to take part in the Philadelphia campaign and saw action at the Battle of Brandywine in September 1777, the Battle of Paoli later that month and the Battle of Germantown in October 1777. The regiment was transferred to the West Indies in November 1778 and saw action at the Battle of St. Lucia in December 1778. Most of the regiment were captured at the siege of Brimstone Hill in February 1782 during the French invasion of Saint Kitts. The regiment adopted a county designation as the 55th (the Westmoreland) Regiment of Foot in August 1782.