In 1787 the Duke was made Generalfeldmarschall (field marshal) in the Prussian army. Frederick William II of Prussia appointed him as commander of a 20,000-strong Prussian force which was to invade the United Provinces of the Netherlands (The Dutch Republic). The goal was to suppress the Patriots of the Batavian Revolution, restoring the authority of the stadtholder William V of the House of Orange. Much of the country was in open revolt against William, whose personal troops were unable to quell the Patriot militias and the various Dutch provinces refused to aid him. The Encyclopædia Britannica described the Duke's invasion: "His success was rapid, complete and almost bloodless, and in the eyes of contemporaries the campaign appeared as an example of perfect generalship". The Patriots were out-manoeuvred and overwhelmed: their militias were unable to put up any real resistance, were forced to abandon their insurrection, and many Patriots fled to France. The Duke's forces entered the Netherlands on 13 September and occupied Nijmegen that day. The largest Patriot force, 7,000 men under the Rhinegrave of Salm, was quickly out-manoeuvred and forced to abandon Utrecht, which the Duke occupied on 16 September. The Prussian force captured Gorcum on the 17th after a short artillery bombardment, followed by Dordrecht on the 18th and Delft on the 19th. They entered The Hague on the 20th, from which the Patriots had been forced to withdraw following a loyalist insurrection on the 17th. Amsterdam, the last city occupied by the Patriots, surrendered on 10 October. The campaign had taken less than a month. William V was restored to power, which he was to hold until 1795. Both contemporaries and historians have praised the Duke's decisive campaign, in which he manoeuvred to concentrate his forces and achieve overwhelming local superiority, before moving on to the next city. He also received credit for the low number of casualties; one British observer suggested that "the sap of the trees was the only blood shed" (an exaggeration), referring to the wooden palisades and batteries constructed by both sides. War of the First Coalition At the outbreak of the War of the First Coalition in the early summer of 1792, Ferdinand was poised with military forces at Coblenz. After the Girondins had arranged for France to declare war on Austria, voted on 20 April 1792, the Catholic Holy Roman Emperor Leopold II and the Protestant King of Prussia Frederick William