German submarine U-48 was a Type VIIB U-boat of Nazi Germany's Kriegsmarine during World War II, and the most successful that was commissioned. During her two years of active service, U-48 sank 51 ships for a total of 299,477 GRT and 1,060 tons; she also damaged four more for a total of 27,877 GRT over twelve war patrols conducted during the opening stages of the Battle of the Atlantic.

U-48 was built at the Germaniawerft in Kiel as yard number 583 during 1938 and 1939, being completed a few months before the outbreak of war in September 1939 and given to Kapitnleutnant (Kptlt.) Herbert Schultze. When war was declared, she was already in position in the North Atlantic, and received the news via radio, allowing her to operate immediately against Allied shipping.

SS City of Benares was a British steam-powered ocean liner, built for Ellerman Lines by Barclay, Curle & Co of Glasgow in 1936. During the Second World War the City of Benares was used as an evacuee ship to transport 90 children from Britain to Canada. The ship was torpedoed and sunk in September of 1940 by the German submarine U-48 with the loss of 258 people out of a complement of 406, including the death of 77 of the evacuated children. The sinking caused such public outrage in Britain that it led to Winston Churchill cancelling the Children's Overseas Reception Board (CORB) plan to relocate British children abroad.