RMS Lancastria (later HMT Lancastria) was a British Cunard liner commandeered by the UK Government for war. She was sunk on 17 June 1940 during World War II, sending at least 4,000 people to their deaths, and possibly many more. It is the greatest ever loss of life in the sinking of a single British ship, claiming more lives than the combined losses of the RMS Titanic (1,523 passengers and crew) and RMS Lusitania (1,200 passengers).