His Majesty's hired armed brig Louisa served the British Royal Navy under contract from 25 May 1799 to 13 November 1801. She was the former mercantile brig Gambier, of 18492⁄94 tons (bm), and was armed with sixteen 18-pounder carronades. Her first commander was Lieutenant Burlton. He sailed Louis on 2 July 1799 from Plymouth with despatches for Earl St Vincent. She returned to Plymouth from the [Gibraltar] Straits on 2 August. Louisa was at Gibraltar station on the occasion of the two battles in Algeciras Bay.(Main article: Algeciras Campaign)