The Royal Scots Fusiliers was a line infantry regiment of the British Army that existed from 1678 until 1959 when it was amalgamated with the Highland Light Infantry to form the Royal Highland Fusiliers. In 1751, the system whereby regiments were numbered by seniority was formalized and it became the 21st Regiment. With the exception of the capture of Belle Île in 1761 during the 1756–63 Seven Years' War, the next 20 years were spent on garrison duty in Gibraltar, Scotland, West Florida and Quebec before returning to England in 1773. The regiment saw action at the Siege of Fort Ticonderoga in July 1777 during the American Revolutionary War, took part in the Siege of Bergen op Zoom in March 1814 during the Napoleonic Wars and saw combat at the Battle of New Orleans in January 1815 during the War of 1812.