Oldenburg är en distriktsfri stad i delstaten Niedersachsen i nordvästra Tyskland, belägen väster om Bremen. Stadens officiella namn är O. Staden har 160 000 invånare och är därmed Niedersachsens fjärde största stad.
The city is the place of origin of the House of O . Before the end of the German Empire (1918), it was the administrative centre and residence of the monarchs of O .
Archaeological finds point to a settlement dating back to the 8th century. The place was first mentioned in 1108 as Aldenburg in connection with Elimar I (also known as Egilmar I) who is now commonly seen as the first count of Oldenburg. The town gained importance due to its location at a ford of the navigable Hunte river. Oldenburg became the capital of the County of Oldenburg (later Duchy, Grand Duchy, and Free State), a small state in the shadow of the much more powerful Hanseatic city of Bremen.
In the 17th century, Oldenburg was a wealthy town in a time of war and turmoil and its population and power grew considerably. In 1667, the town was struck by a disastrous plague epidemic and, shortly after, a fire destroyed Oldenburg. The Danish kings, who were also counts of Oldenburg at the time, were not much interested in the condition of the town and it lost most of its former importance. In 1773, Danish rule ended. It was only then that the destroyed buildings in the city were rebuilt in a neoclassicist style. (In German, the ‘neoclassicist style’ of that period would usually be called klassizistisch, while neoklassizistisch specifically refers to the classicist style of the early 20th century.)
After German Emperor Wilhelm II was forced to abdicate following the exhaustion and defeat of the German Empire in World War I, monarchic rule ended in Oldenburg as well with the abdication of Grand Duke Frederick Augustus II of Oldenburg (Friedrich August II von Oldenburg) on 11 November 1918. The Grand Duchy of Oldenburg now became the Free State of Oldenburg (Freistaat Oldenburg), the city remained the capital.
In the 1928 city elections, the Nazi Party received 9.8% of the vote, enough for a seat on the Oldenburg city council. In the September 1930 Oldenburg state elections, the Nazi Party’s share of the vote rose to 27.3%, and on May 29, 1932, the Nazi Party received 48.4% of the state election, enough to put the Nazi party in charge of forming a state government and, significantly, making Oldenburg the first state in the country to put the Nazis in power based on electoral turnout. By that fall, a campaign of Aryanization began, forcing the sale of formerly Jewish-owed properties at steep discounts.
In 1945, after World War II, the State of Oldenburg was part of the British zone of occupation. The British military government of the Oldenburg region resided in the city. Several displaced persons camps were set up in the city that had suffered only 1.4% destruction during the bombing campaigns of World War II. About 42,000 refugees migrated into Oldenburg, which raised the number of residents to over 100,000. In 1946, the Free State of Oldenburg was dissolved, and the area became the ‘Administrative District’ of Oldenburg (Verwaltungsbezirk Oldenburg) as part of the newly formed federal German state of Lower Saxony (Niedersachsen). The city was now capital of the district. In 1978, the district was dissolved and succeeded by the newly formed Weser-Ems administrative region (Regierungsbezirk Weser-Ems), again with the city as administrative capital. The State of Lower Saxony dissolved all regierungsbezirks by the end of 2004 in the course of administrative reforms.