The French garrison in Valletta signed the surrender (or ‘capitulation’, to use the language in this dispatch) on 5 December 1800, and Malta then became a UK protectorate.
Malta had been occupied by the French in May 1798, when an invasion fleet of 30,000 men led by Napoleon sailed from Toulon.
Here is a dispatch, written on 5 September 1800 by Major General Pigot to General Sir R. Abercrombie, which describes the surrender of the French forces at Valletta.
Hampshire Chronicle – Monday 13 October 1800
Image © THE BRITISH LIBRARY BOARD. ALL RIGHTS RESERVED.
http://www.britishnewspaperarchive.co.uk/viewer/bl/0000230/18001013/009/0004