A British Super-Submarine

A British Super-Submarine', circa 1914-1918, (1919). M-class submarine: 'Her armament consists of a 12" gun weighing 50 tons and firing a projectile 850 lbs. She is in reality a sumbersible monitor, and it needs no imagination to visualise the effect of a fleet of such monsters operating in German waters had they had an opportunity to do so.' M1 was the only one of her class to enter service before the end of World War I but did not see action. From "The History of the Great European War: its causes and effects", Vol. VII, by W. Stanley Macbean Knight. [Caxton Pulishing Company, Limited, London, 1919]. Artist Unknown. (Photo by The Print Collector/The Print Collector/Getty Images)