Siege of Dorsten

The Siege of Dorsten (German: Belagerung von Dorsten) was a military conflict that lasted from 16 July 1641 to 19 September 1641 during the Thirty Years' War in Europe. The opposing sides were the Landgraviate of Hesse-Cassel and the Holy Roman Empire of the German Nation.

According to a judgement by the Vienna Supreme Court (Wiener Hofgericht), Hesse-Cassel had to cede Upper Hesse, which included the University of Marburg, to Hesse-Darmstadt. In return for this substantial loss, in the Treaty of Werben on 22 August 1631, King Gustavus Adolphus of Sweden promised to grant the state of Hesse-Cassel, various territories including parts of the Prince-Bishopric of Münster (Hochstift Münster) and Vest Recklinghausen (governed by the Electorate of Cologne) if he were victorious in the Thirty Years' War.

On 9 February 1633, Hesse-Cassel captured the town of Dorsten without resistance from the Electorate of Cologne and the Vest of Recklinghausen and, in the years that followed, it was turned into the strongest fortress in the region by the Hessian, Colonel Dalwig, and Johann Adriansch. As early as 1636, an attempt was made under the command of Johann von Götz to recapture Dorsten, but he was met with failure.

On 16 July 1641 a second siege of the town of Dorsten was begun by imperial Field Marshal Melchior, Count of Hatzfeldt and imperial Feldzeugmeister, Alexander II of Velen, with some 20,000 soldiers. This attack was started because, earlier, the Hessian lieutenant general, Kaspar, Count of Eberstein had moved off with a portion of his troops to participate in the Siege of Wolfenbüttel. Whilst the main body of imperial troops were also engaged at Wolfenbüttel, Hatzfeld positioned his forces south of Dorsten, whilst Velen deployed to the north. The Imperial Artillery took post to the northeast amongst the sand hills, initially with 14 cannon. They were later reinforced by the Electorate of Cologne bringing the total to 30 guns. In a letter from the imperial Generalwachtmeister, Freiherr von Wendt, dated 16 July, to the mayor and town council of Recklinghausen, he demanded the following supplies for the provision of his soldiers outside Dorsten: 3,000 pounds of bread, 16 tonnes of beer, four head of cattle, 15 sacks of oats and several "kitchen items". The Barony of Lembeck (Herrlichkeit Lembeck) also had to supply food. In early August, Hatzfeld also fetched four half-kartouwen and two fire mortars (Feuermörser) from Kaiserswerth. The soldiers, who came from the 12th Regiment of Infantry and 10th Regiment of Cavalry, constructed extensive siegeworks around the town.

The Hessian defenders were commanded by Senior Commandant (Oberkommandant) Johann von Geyso and Commandant Emmanuel Kotz with 2,000 soldiers, 400 of whom had previously been redeployed from Kalkar. Other relief contingents called up by the Hesse-Cassel regent, Amalie Elisabeth of Hanau-Münzenberg, were either very small in number (250 men under Colonel Carl von Rabenhaupt from Haltern and Borken) or arrived too late (troops under the command of Ernest Albert of Eberstein from Wolfenbüttel). On 25 August the first breach was made west of the Lippe Gate with 2,000 artillery shells, destroying the last line barrier. Once this breach had been widened by cannon fire and plans for an assault with initially 2,000 musketeers and 1,500 cuirassiers got under way, the Hessian commandants opened negotiations over the terms of surrender on 18 September with Field Marshal von Hatzfeld.

The siege ended on 19 September. The Hesse-Cassel garrison were given safe passage for their remaining personnel comprising 650 men plus administrators and families. The Theatrum Europaeum recorded that the town of Dorsten had become a "lamentable ruin" as a result of the siege.

With the capitulation of Dorsten, Hesse-Cassel had lost the most important fortress on the right bank of the Lower Rhine and, in the aftermath, concentrated their efforts in the Hessian War, together with France and Saxe-Weimar, on the left bank possessions of the Archbishopric of Cologne under Ferdinand of Bavaria and the neutral Duchy of Jülich under Wolfgang William.