Naval mine ship, HMHS "Britannic", which was the sister ship of the RMS "Titanic." During World War II, the U-boat fleet, which dominated much of the battle of the Atlantic, was small at the beginning of the war and much of the early action by German forces involved mining convoy routes and ports around Britain. German submarines also operated in the Mediterranean Sea, in the Caribbean Sea, and along the U.S. coast. Initially, contact mines (requiring a ship to physically strike a mine to detonate it) were employed, usually tethered at the end of a cable just below the surface of the
German hospital ship Ophelia raising suspicions as her supposed task of searching for German survivors was not completed. Under Article 4 of Hague Convention X, hospital ships cannot be seized but they can be inspected by enemy craft. The British Admiralty seized the "Ophelia" as a prize of war, rather than as a hospital ship. Their reasons for doubting her status as a hospital ship were the dumping of documents by the crew, the transmission of a coded message before the boarding, and the destruction of the ship's wireless set. Furthermore, the ship was not included in the list of hospital ships that were