The Hannover was a 5,537 BRT Lloyd ship by Bremer Vulkan which entered service in 1939 under Kapitan Wahnschaff. While attempting to return as a blockade-runner to Germany from the West Indies she was sighted and ordered to stop on the night of 7/8 March 1940 by the light cruiser HMS Dunedin and the (Canadian) destroyer HMCS Assiniboine. The order was ignored and she unsuccessfully attempted to escape, whereupon the captain instructed that the sea cocks be opened and the ship be set on fire. Nevertheless the British boarded her, closed the sea cocks and fought for four days against the fire, eventually saving the ship which was then towed to Jamaica.
She was named Sinbad upon capture but soon re-named Empire Audacity and was commissioned as an "Ocean Boarding Vessel" in November 1940. She was then given over to Blyth Shipbuilding Ltd in January 1941 for conversion to an escort carrier. Conversion was completed in time for commissioning on 20 June 1941. She was re-named HMS Audacity on 30 July 1941.
She sailed with her first convoy to Gibraltar in September 1941. On 21 September, during her first run, one of her aircraft shot down a Condor bomber which had made a bombing run on the convoy rescue ship Walmer Castle, although not without the ship being damaged sufficiently to be sunk. She sailed with two more convoys.
She was torpedoed and sunk some 500 miles west of Cape Finisterre on 21 December 1941 by three torpedoes from U-751 under Kapitanleutnant Gerhard Bigalk whilst on the convoy HG 76. She sank in 70 minutes.