"Courbet" was seized there, as part of Operation Catapult, by British forces on 3 July to prevent French ships from falling into German hands after the French surrender in late June. The ship was given to the Free French a week later, who used her as an anti-aircraft battery in Portsmouth, until she was disarmed on 31 March 1941, and used as an accommodation ship. At Loch Striven, Scotland, she was used as a target for the "Highball" bouncing bomb trials between 9 May and December 1943. "Highball" was a smaller version of "Upkeep" used in Operation Chastise, also known as the Dambuster Raid. "Courbet" remained in use as a depot and target ship until she was earmarked for use as a "Gooseberry" breakwater at Sword Beach during the Normandy landings. The ship had to be towed from Weymouth on 7 June by a pair of British tugboats as her engines and boilers had been removed earlier and replaced with concrete. She was scuttled on 9 June off Sword Beach and was hit by Neger manned torpedoes during the nights of 15–16 and 16–17 August. As such, she was probably the only ship ever attacked by secret weapons of both sides during the conflict. She was slowly scrapped in place after the war; the demolition was completed in 1970.