 The submarine was ordered as U-11 from Germaniawerft of Kiel as the last of five boats of the U-7 class for the Austro-Hungarian Navy. After the outbreak of World War I in August 1914, the Austro-Hungarian Navy became convinced that none of the submarines of the class could be delivered to the Adriatic via Gibraltar. As a consequence, the entire class, including U-11, was sold to the German Imperial Navy in November 1914. Under German control, the class became known as the U 66 type and the boats were renumbered; U-11 became U-70, and all were redesigned and reconstructed to German specifications. U-70 was launched in July 1915 and commissioned in September. As completed, she displaced 791 tonnes (779 long tons), surfaced, and 933 tonnes (918 long tons), submerged. The boat was 69.50 metres (228 ft) long and was armed with five torpedo tubes and a deck gun.
