Swedish Wars on Bremen The Swedish Wars on Bremen were fought between the Swedish Empire and the Hanseatic town of Bremen in 1654 and 1666 . Bremen claimed to be subject to the Holy Roman Emperor , maintaining Imperial immediacy , while Sweden claimed Bremen to be a mediatised part of her dominions of Bremen - Verden , themselves territories immediately beneath the emperor . Sweden was able to gain some territory , but despite forcing a formal oath of allegiance on Bremen , did not gain control of the town . Background . When in 1648 the Peace of Westphalia ended the Thirty Years ' War , the parties agreed that the prince - bishoprics of Bremen and Verden were to become dominions of Sweden . The peace treaty had been prepared at a congress throughout the final years of the war . During the negotiations , several mostly Hanseatic cities requested that they become Imperial cities , with only Bremen being successful : Ferdinand III , Holy Roman Emperor accepted Bremen as a Free imperial city in 1646 . A respective document was signed in Linz on 1 June , with the aim of preventing Sweden from gaining the city . In turn Bremen , among other concessions , paid about 100 . 000 taler s . Owing to Swedish diplomatic efforts however , the text of the 1648 treaty did not determine whether or not Bremen was to be included in the future Swedish dominion . The Prince - Archbishopric of Bremen , northerly and easterly neighbouring the city ' s territory , had been occupied by Sweden since 1646 / 47 . Swedish forces had then expelled the forces of Prince - Archbishop Frederick II , Prince of Denmark , officiating from 1637 to 1648 . On 18 February 1647 , the emperor accepted Sweden ' s annexation of the prince - archbishopric ' s territory as a secularized duchy . After the war a dispute about custom collection between Bremen and the emperor led to the latter imposing an Imperial ban on the city in 1652 / 53 . Sweden , which had never accepted Bremen ' s Imperial immediacy , attacked in 1654 . First war ( 1654 ) . Swedish forces commanded by Hans Kristofer von Königsmark occupied part of the territory held by the city , but did not attack the city itself . Bremen recruited mercenaries and strengthened its defensive works . Without engaging in any major confrontation , the parties agreed on the Treaty of Stade ( ) on 28 November . It was agreed that Sweden kept occupied Bederkesa and Lehe , and Bremen had to pledge allegiance to the Swedish king Charles X Gustav . Bremen did so on 6 December . Second war ( 1666 ) . In 1665 , Bremen refused to pledge allegiance to Charles X Gustav ' s successor , Charles XI of Sweden . In March , the Swedish riksråd decided to wage war . Thereupon , 12 , 000 Swedish troops were transferred to the Duchy of Bremen by the end of the year . In January 1666 , Carl Gustaf Wrangel departed from Swedish Pomerania to command the Swedish army , which in early 1666 numbered 14 , 000 troops . By summer , all of the city of Bremen ' s territory was occupied , except the city itself . The Swedish chancellor of Bremen - Verden , Esaias von Pufendorf , went to the court in Paris to build an alliance with France . The Swedish position was that France had to intervene on the Swedish side , since Bremen was Swedish according to the Peace of Westphalia , of which France was a guarantor . Pufendorf was however told by Hugues de Lionne that France would not hesitate to declare openly that she read the treaty as Bremen being an Imperial city , rather than provoke a new great war with the Holy Roman Empire and the Dutch Republic with an assault Sweden and France could hardly win . Lionne said Sweden would be better off waiting for a situation when the Dutch and the neighboring German principalities were weak , and then take the city of Bremen by surprise . The city of Bremen on the other side was successful in gathering allies , most notably Brunswick - Lüneburg ( Celle ) and the Electorate of Cologne , who raised a relief army . Brandenburg , Denmark and the Dutch Republic joined the anti - Swedish alliance . Wrangel failed to take the city , and initiated negotiations at his headquarters in Habenhausen . On 14 November , the Peace of Habenhausen was signed : Swedish Bremen - Verden was obliged to destroy the fortresses built close to the city . Bremen had to dispense with its status as an Imperial city during the contemporary sessions of the Imperial Diet , which were scheduled to last until the end of the 17th century . Bremen was also banned from emitting representatives to the Diet of the Lower Saxon Circle . What could not be foreseen at the time of the peace was that the Imperial Diet was to become the " Perpetual Diet of Regensburg " , lasting until the dissolution of the Holy Roman Empire in 1806 . Bremen further had to cede its territories north of the city and at the lower Weser river . However , the city itself with a number of villages around , maintained its independence . When in 1700 Charles XII of Sweden asked " Bremen - Verden ' s General Government " what to do about Bremen ' s independence , the General Government recommended to concede its status as a " Free imperial City " . Aftermath . In 1672 , Sweden founded Carlsburg at the confluence of the Weser and Geeste rivers to compete with Bremen , but the settlement did not prosper . Sweden later lost all of Bremen - Verden during the Great Northern War ( 1700 – 1721 ) .