The senior partner in the amalgamated Wiltshire Regiment was the 62nd Regiment of Foot. The 62nd was formed in 1756, originally as the second battalion of the 4th Regiment of Foot. In 1758, the battalion was redesignated as the 62nd Regiment of Foot. Although a regiment of the line, many of its companies were initially deployed as marines, serving with Admiral Boscawen's fleet during the Siege of Louisbourg in 1758. The balance of the regiment remained in Ireland where they defended Castle Carrickfergus from a French invasion force in 1758.