The 42nd Regiment of Foot was a Scottish infantry regiment in the British Army also known as the Black Watch. Originally titled Crawford's Highlanders or the Highland Regiment and numbered 43rd in the line, in 1748, on the disbanding of Oglethorpe's Regiment of Foot, they were renumbered 42nd, and in 1751 formally titled the 42nd (Highland) Regiment of Foot. The 42nd Regiment was one of the first three Highland Regiments to fight in North America. The unit was honoured with the name Royal Highland Regiment in 1758. Its informal name Black Watch became official in 1861. In 1881, the regiment was amalgamated with 73rd (Perthshire) Regiment of Foot under the Childers Reforms into The Royal Highland Regiment , being officially redesignated The Black Watch in 1931. In 2006, the Black Watch became part of the Royal Regiment of Scotland.

The 73rd Regiment of Foot was an infantry regiment of the British Army, raised in 1780. Under the Childers Reforms it amalgamated with the 42nd Regiment of Foot to form the Black Watch in 1881.