In 2016, in the centenary year of the Battle of Jutland, the hulks of two previously unrecognised warships were identified in the intertidal mud of Portsmouth Harbour. First abandoned in the 1920s on the shore of Whale Island, the identity and significance of these vessels slowly fell out of memory and into complete obscurity. This talk explains the surprising story of how two German warships, one of which survived the Battle of Jutland, came to be in Portsmouth Harbour and how they were identified.