Bremerhaven (ˌbʁeːmɐˈhaːfn̩, Bremener Harbour; Bremerhoben) is a city at the seaport of the Free Hanseatic City of Bremen, a state of the Federal Republic of Germany.
It forms a semi-enclave in the state of Lower Saxony and is located at the mouth of the Weser on its eastern bank, opposite the town of Nordenham. Though a relatively new city, it has a long history as a trade port and today is one of the most important German ports, playing a role in Germany's trade.
Wesermünde was a neighbouring city created in 1924 through the merger of Geestemünde and Lehe. In 1939, Bremerhaven was incorporated into Wesermünde, but in 1947 the cities were collectively renamed as Bremerhaven and returned to the Free Hanseatic City of Bremen.
The town was founded in 1827, but neighboring settlements such as Lehe were in the vicinity as early as the 12th century, and Geestendorf was "mentioned in documents of the ninth century". These tiny villages were built on small islands in the swampy estuary. In 1381, the city of Bremen established de facto rule over the lower Weser stream, including Lehe, later therefore called Bremerlehe. Early in 1653, Swedish Bremen-Verden's troops captured Bremerlehe by force.
The Emperor Ferdinand III ordered his vassal Christina of Sweden, then Duchess regnant of Bremen-Verden, to restitute Bremerlehe to Bremen. However, Swedish Bremen-Verden began the First Bremian War (March – July 1654). In the subsequent peace treaty (de; November 1654) Bremen had to cede Bremerlehe and its surroundings to Swedish Bremen-Verden. The latter developed plans to found a fortified town on the site, and much later this location became the present-day city of Bremerhaven. In 1672, under the reign of Charles XI of Sweden, in personal union Duke of Bremen-Verden—colonists tried unsuccessfully to erect a castle (named Carlsburg after Charles XI) there; this fortified structure was meant to protect, as well as control shipping heading for Bremen.
Finally, in 1827, the city of Bremen under Burgomaster Johann Smidt bought the territories at the mouth of the Weser from the Kingdom of Hanover.