The Roman Catholic Prince-Bishop of Münster, Christoph Bernhard von Galen, who was intent on extending his power and who, until 22 April 1674, sided with France in battle against the Netherlands, signed an agreement on 7 June 1675 with the imperial court in Vienna that obliged him to supply 9,000 troops "to the Emperor and for Imperial Service".
As a result of this obligation, the bishop was made to participate in the war against Sweden.
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.
Brunswick-Lüneburg, which hitherto had been on the Swedish side, therefore, agreed to remain neutral in the upcoming fight against Sweden.
On 25 September at Bremen, Münster's artillery fired across the Weser.