From 15 September 1675 to 13 August 1676[6] an anti-Swedish coalition comprising Brandenburg-Prussia, the neighbouring imperial princedoms of Lüneburg and Münster, and Denmark-Norway, conquered the Duchies of Bremen and Verden.

Following its conquest it remained in allied hands until the end of the war in 1679, but was then fully returned to Sweden in the wake of the Treaties of Nijmegen.

In order to relieve her increasingly stretched forces, therefore, France urged its traditional ally, Sweden, to go to war against her enemies, who, in addition to the States General, included the House of Habsburg and the Electorate of Brandenburg.

Sweden's chances in the Duchy of Bremen-Verden, therefore, lay principally in the strength of her own fleet, which was to have ensured a military victory by dispatching additional troops from the motherland.

The number of the fortified places would force her potential opponents, to fight a series of arduous, small sieges, but it also fragmented the troops available to the defenders and prevented them from forming a mobile field army.

[9] On 11/21 September 1675 a treaty of neutrality was signed between the Allies, the Prince-Bishopric of Münster, Denmark and Brandenburg on the one hand and John Frederick of Brunswick-Lüneburg on the other.

That treaty between the four allies was signed primarily because it was in the political interests of the imperial princes involved, rather than in discharge of their obligation to defend the circle or empire.

A Brandenburg force of 1,600 infantry and 700 cavalry under Major General Freiherr von Spaen, coming from Westphalian territory, also arrived in Bremen at the end of September.

The Münster troops under Prince-Bishop von Galen marched from neutral Bremen to the fortress of Langwedel on the Weser, capturing it on 27 and 28 September.

After occupying an important eminence in front of the town that same day, the Allies drew up all their artillery of 14 mortars and 37 cannon into battery positions.

Because the shelling had already resulted in heavy damage, the Buxtehude commandant, Hamelton, was forced to surrender the town having been implored by its citizens and his German mercenaries who had learned of the pronouncement of the Imperial Ban on Sweden.

The first landing operation, at the end of September, was carried out near Carlshagen by a Brandenburg formation under Admiral Simon de Bolfey, in order to conquer the strategically important Carlsburg Fortress on the Weser.

Because the Swedish commander of Carlsburg, which was relatively strongly defended by about 800 soldiers, refused to surrender, the Brandenburg admiral, de Bolfey, had his troops erect earthworks in front of the town and, on 30 September, opened fire with several salvoes from his ships' guns.

However, on the same day the landing force pulled back from its positions in front of the fortress, in the course of which 30 Brandenburg soldiers switched sides to join the Swedes.

The naval blockade of Carlsburg was lifted and the seven Brandenburg ships repaired instead to the River Elbe in order to cut off the seaward supply route to the town of Stade.

In October about 3,000 men[4] of the Principality of Lüneburg under the command of Duke George William of Brunswick-Lüneburg arrived in the theatre of war from the Rhineland.

The Stade garrison under Field Marshal Henrik Horn, the Swedish governor general of the Duchy, had 5,624 soldiers and 600 militia at his disposal.

Repeated attacks on the fortress of Stade on 6 and 7 November 1675 were unsuccessful, and the Allies could not agree on continuing the siege of the town because of its stubborn resistance and the onset of winter.

A lack of ammunition, food and soldiers resulted in the surrender of the fortress on 22 January by its commander, the Frenchman, Colonel Jean Mell, to the united Münster, Danish and Lüneburg siege troops.

[18] Because the Prince-Bishopric of Münster and the Duchy of Lüneburg had agreed in advance to exclude Denmark and Brandenburg from the future division of Bremen-Verden, there were serious arguments amongst the Allies, which affected and endangered the continuation of hostilities against Sweden.

The statthalter ("governor") of the Netherlands, William III of Orange, proposed that all fortresses in Bremen-Verden should be slighted, to negotiate the final apportionment of territory at the peace congress in Nijmegen and to transfer provisional administration of both duchies to Lüneburg-Celle and Münster.

Brandenburg and Denmark were expressly entitled to retain their rights to territorial interests in Bremen-Verden if, contrary to expectations, they did not achieve "compensation" in Swedish Pomerania and Scania.

[19] Although Brandenburg's envoy wanted to reach a provisional breakdown of the areas in question in the Hague, on 28 March he gave his approval to the treaty because he saw no other way to achieve an end to the dispute between the Allies, something which was essential for the continuation of the campaign.

Although the Elector of Brandenburg did not ratify the decision of his envoy, he dropped his objections to the deployment of Lüneburg auxiliaries to Bremen-Verden in the light of the favourable progress being made in the war against Sweden in Swedish Pomerania.

On 23 April the Swedes carried out a new raid with 300 horsemen, but were again driven back after initial success, with a loss of 46 men, according to contemporary sources.

As the supply situation in the town became ever more critical, the Stade citizens and the garrison's governor general, Horn, were forced to negotiate with their besiegers.

However, they were delayed at the behest of population who, despite the tougher conditions preferred to be garrisoned by Protestant Lüneburg troops rather than Catholic Munster forces.

During the occupation of Stade, Prince-Bishop von Galen led a re-Catholicization of the area he controlled, and Catholic services were reintroduced in many places.

After French troops had invaded Westphalia, the new Prince-Bishop of Münster, Ferdinand of Fürstenberg returned all his conquests to Sweden in the Peace of Nijmegen on 29 March 1679.

France promised the Bishop of Munster that they would work for the preservation of the newly created Catholic institutions in the Duchy of Bremen and Principality of Verden.