German submarine U-704 was a Type VIIC U-boat of the German Kriegsmarine during World War II. Commissioned on 18 November 1941 under the command of Kapitänleutnant Horst Kessler, U-704 carried out training operations as part of the 8th U-boat Flotilla until June 1942. U-704 set out on its first patrol, a transit to its operational base at Saint-Nazaire on 30 June 1942. During this patrol, U-704 formed part of wolfpack "Wolf" which was to patrol between Iceland and Greenland, out of the range of allied air cover. On 26 July 1942, U-704 torpedoed the British freighter Empire Rainbow, part of convoy Convoy ON-113. Empire Rainbow had already been damaged by a torpedo from U-607, and U-704's torpedo sank the freighter.