In the late Middle Ages, its governing merchant guilds were at the centre of the Hanseatic League, which sought to monopolise the North Sea and Baltic trade.
To establish and confirm its independence, the city had to contend first with the Prince-Archbishop of Bremen, and then with the Swedes, who had become the masters of the surrounding, former episcopal, duchies after the Thirty Years' War.
Thanks to new sea wharves and anchorage at Bremerhaven, the city became Germany's main port of emigration to the Americas, and an entrepôt for her late developing colonial trade.
From the late 1950s, the post-war Wirtschaftswunder drew workers to the city from Turkey and Southern Europe, so that, combined with refugees resettled in the 21st century, around a third of Bremen's current population is of recent non-German origin.
In 888, at the behest of Archbishop Rimbert, Kaiser Arnulf of Carinthia, the Carolingian King of East Francia, granted Bremen the rights (confirmed in 965) to hold its own markets, mint its own coins and devise its own customs laws.
In 1186 the Prince-Archbishop Hartwig of Uthlede and his bailiff in Bremen confirmed the Gelnhausen Privilege, by which Frederick I Barbarossa granted the city considerable legislative and fiscal autonomy.
Of equal importance to the powerful merchant guilds, or Hansa, of Bremen was the League's ability to control the North Sea salt-fish trade, and above all the Scania Market.
[7] As for the League in general, much of the drive for the co-operation between otherwise rival cities derived from the fragmented nature of existing territorial governments, which had failed to provide security for trade.
However, the League's importance declined in Bremen in the 16th century, as the United Dutch Provinces entered the competition and as greater princely authority consolidated, creating powerful monarchies such as Sweden, Denmark-Norway, Brandenburg-Prussia and England.
As a measure of its new power and independence, in 1404 the city replaced its old wooden statue of Roland with a larger limestone model, which still stands today before the Rathaus in the central market place.
[9]: 30 Bremen, long hostile to its Prince-Archbishop and the temporal power and pretensions of the Church, readily embraced the Protestant Reformation, as it swept across Northern Germany in the late 1520s.
In 1532, Bremen's burghers forcefully interrupted Catholic Mass in St Peter's cathedral, the Bremer Dom, and prompted a pastor to hold a Lutheran service in its place.
However, once Swedish forces had gained control of the former episcopal territories around the city (an occupation that was confirmed by the Treaty Westphalia in 1648), Bremen sensed a new threat to its independence.
In February 1654 the emperor granted Bremen a seat and vote within the Imperial Diet for the first time, and demanded of Christina of Sweden that she return Bremerlehe and compensate the city.
Despite such orders, further fighting ensued, and Bremen was eventually forced to pay tribute and levy taxes to Swedish Bremen-Verden, as well as cede territory around Bederkesa and Bremerlehe.
[15] As part of his effort to enforce the Berlin Decree closing the European continent to British trade, Napoleon annexed Bremen in 1811, as capital of the Département de Bouches-du-Weser (Department of the Mouths of the Weser).
[23] Following defeat in World War I, and the chaos induced by naval and army mutinies, as well as hardships from a prolonged British blockade, Bremen was briefly governed by a revolutionary workers' and soldiers' council.
[28] The following morning a large crowd led by Nazi brownshirts gathered in the market square, calling for the resignation of the Senate and hanging swastika flags on the facade of the city hall.
However, since the Senate rejected the other demands, that evening the Reich Interior Minister Wilhelm Frick intervened and appointed Richard Markert as the Reichskommissar in charge of the Bremen police.
[30] On 31 March 1933, the Nazi government enacted the Provisional Law on the Coordination of the States with the Reich, which mandated the reconstitution of the Bürgerschaft on the basis of the recent Reichstag election.
Henrich Focke, Georg Wulf and Werner Naumann had founded Focke-Wulf Flugzeugbau AG in Bremen in 1923 (the aviation company that, beginning in 1964, entered a series of mergers that incorporates it into today's Airbus).
[38] The villages of Grohn, Schönebeck, Aumund, Hammersbeck, Fähr, Lobbendorf, Blumenthal, Farge and Rekum [de; nds] became part of the city of Bremen in 1939.
On 1 August 1945, the US military government appointed Wilhelm Kaisen (SPD) (Senator for social services before 1933) mayor of Bremen, a position he continued to cover through several elections until his retirement in 1965.
On 20 November 1945, a group of Polish DPs from Tirpitz Camp invaded a house where a family of 13 people were staying that night, including children and young adults.
43 year-old Wilhelm Hamelmann was the sole survivor, attracted considerable attention by publicly forgiving the perpetrators and pleading for them to be pardoned, despite them killing his wife and children.
[41] Bremen's signature Renaissance-fronted gothic Town Hall (Rathaus), the statue of Roland (1404) (symbol of the city's independence), and the 11th-century cathedral (Bremer Dom) survived Allied bombing.
Limited efforts were made to restore other damaged structures of the old city, as priority was given to the construction of new much-needed housing, in light of the increase in population and arrival of many German refugees from eastern territories annexed by Poland and the Soviet Union.
Specialist construction yards, ship outfitters and parts suppliers remain,[43] but AG Weser (which employed 16,000 workers at its peak) and Bremer Vulcan, Bremen's two major shipbuilders, closed in 1983 and 1997 respectively.
Semi and unskilled harbour workers found it very difficult to re-enter the labour market, and unemployment—for a period in the 1980s almost double the West German average—remained comparatively high.
The idea of cutting subsidies and reorienting economic policy was particularly difficult for the Social Democrats, given their strong traditional links to manual workers and trade unions.