HMS E20 (Lt Cdr C Warren) was torpedoed in the Sea of Marmora by the German submarine UB14 on 5 November 1915. E20 had been due to rendezvous with the French submarine TURQUOISE, but the French boat had grounded and had been abandoned under fire. The enemy were able to capture information relating to the rendezvous and set a trap for E20.

UB14 lay in wait for the British boat and fired a torpedo at her from a range of 550 yards. Twenty-one men died in the resulting explosion but nine, including the Commanding Officer, were rescued from an oily patch on the surface. One of these survivors, Able Seaman A J Howard, subsequently died from chronic enteritis on 8 February 1917 while in captivity.