U-139, originally designated "Project 46", was a class of large, long-range U-boats built during World War I by the Kaiserliche Marine.
The Type UB III submarine was a class of U-boat built during World War I by the German Imperial Navy.
Germany (Deutschland), officially the Federal Republic of Germany (Bundesrepublik Deutschland), is a sovereign state in central-western Europe.
Laying the keel or laying down is the formal recognition of the start of a ship's construction.
A submarine (or simply sub) is a watercraft capable of independent operation underwater.
The Type II U-boat was designed by Nazi Germany as a coastal U-boat, modeled after the CV-707 submarine, which was designed by the Dutch dummy company NV Ingenieurskantoor voor Scheepsbouw den Haag (I.v.S) (set up by Germany after World War I in order to maintain and develop German submarine technology and to circumvent the limitations set by the Treaty of Versailles) and built in 1933 by the Finnish Crichton-Vulcan shipyard in Turku, Finland.
Lower Upnor and Upper Upnor are two small villages in Medway, Kent, England.
World War I (often abbreviated as WWI or WW1), also known as the First World War, the Great War, or the War to End All Wars, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918.
World War II (often abbreviated to WWII or WW2), also known as the Second World War, was a global war that lasted from 1939 to 1945, although conflicts reflecting the ideological clash between what would become the Allied and Axis blocs began earlier.