Siebethsburg castlepirate stronghold; the Hanseatic League destroyed it in 1433. Four centuries later, the Kingdom of Prussia planned a fleet and a harbour on the North Sea. In 1853, Prince Adalbert of Prussia, a cousin of the Prussian King Frederick William IV, arranged the Jade Treaty (Jade-Vertrag) with the Grand Duchy of Oldenburg, in which Prussia and the Grand Duchy entered into a contract whereby Oldenburg ceded 3.13 square kilometres (1.21 square miles) of its territory at the Jade Bight to Prussia. In 1869 King William I of Prussia (later also German Emperor) founded the town as an exclave of the Province of Hanover and a naval base for Prussia's developing fleet. All the hinterland of the city remained as part of the Duchy of Oldenburg.
, built before 1383, operated as a
A shipbuilding yard developed at Wilhelmshaven, the Kaiserliche Werft Wilhelmshaven (Wilhelmshaven Imperial Shipyard). On 30 June 1934 the "pocket battleship" Admiral Graf Spee was launched at Wilhelmshaven.
In 1937 Wilhelmshaven and Rüstringen merged and the united city, named Wilhelmshaven, became a part of the Free State of Oldenburg.
World War II
In World War II (1939-1945), Allied bombing destroyed two thirds of the town's buildings while the main target Naval Shipyard Wilhelmshaven were still working though there were serious damages. On 28 April 1945, the Canadian First Army captured Emden and Wilhelmshaven, Germany, and took the surrender of the entire garrison, including some 200 ships of the Kriegsmarine. The Poles remained as part of the allied occupation forces until 1947. During World War II Alter Banter Weg (No. 1582 Wilhelmshaven) functioned as a subcamp of the Neuengamme concentration camp.
In 1947 the city council decided to seek a new emblem for the city. After the Control Commission for Germany - British Element (CCG/BE) had rejected several designs, Wilhelmshaven selected the image of a Frisian warrior (Rüstringer Friese), designed after a nail man erected in the city during the First World War to collect war donations.
Between 1947 and 1972 Wilhelmshaven was the home of PRINCE RUPERT SCHOOL, a comprehensive boarding school for children of British Army and RAF personnel serving with BAOR. The school relocated to Rinteln in 1972. There is an active association of former Wilhelmshaven pupils called The Wilhelmshaven Association. After "World War II" the shipyard was totally disarmed under the british Commander in Chief, and of course many military buildings were damaged or vacant. While it was prohibited to develop any kind of military linked business Wilhelmshaven took the chance to establish a convenient location for the Olympia Werke which become one of the most popular and quality typewriter factories in the world. In 1953 7000 worker were employed.