 The British strengthened the islands ' defences , in case of further attacks , and a number of warships patrolled the area to observe French movements and intercept any flotillas of invasion craft . At the Action of 30 May 1798 , this strategy achieved an unexpected success when HMS Hydra intercepted the French frigate Confiante and a corvette off the mouth of the River Dives . The British drove Confiante ashore and boarding parties later burnt her . The islands remained under British occupation without any further French attacks until 1802 . The Peace of Amiens returned the islands to French control ; throughout the Napoleonic Wars of 1803 – 1815 they remained French , protected by a significant garrison . 
