 As a result, the five boats of the class were transferred to the Imperial German Navy on 28 November 1914 after the advance payment of 2 million Kronen had been returned.Germaniawerft was then awarded "Kriegsauftrag D", hence the type was known as "UD".After their purchase, the boats were assigned the numbers "U-66" to "U-70", and the class became known as the U 66 type.