HMS Marmora was a 10,000 ton passenger ship owned by Peninsular & Oriental Steam Navigation Company, but on Aug. 3, 1914 the Admiralty requisitioned her and converted the ship into an Armed Merchant Cruiser. Most of her time was spent in the South Atlantic escorting convoys and searching for the famed raider SMS Möwe. On July 23, 1918 she was south of Ireland when SMS UB-64 slammed a torpedo into her side. Distress signals went out and several destroyers responded to her location, all but ten men were rescued from the sinking ship.

A few days before sinking HMS Marmora, Kapitänleutnant Otto von Schrader and his UB-64 had fired the torpedo which damaged the Justicia and on the same day he sank the sailing vessel Ranger, Marmora was the last ship he sank as commander of UB-64, he was placed in command of SMS U-53 in Aug. 1918. In the Second World War von Schrader was promoted to Admiral and was even awarded the Ritterkreuz (Knight's Cross). He was taken prisoner in Norway after the war and committed suicide there on July 19, 1945.