Not knowing where to offer his services next, Nassau approached the Prussian King Frederick the Great. Frederick appointed Nassau as major general, and instructed him to recruit a dragoon regiment (Dragoon Regiment No. XI) of Prussian and Saxon officers. He also received ten talers for every man he recruited. Nassau had been successful in Saxony and maintained his contacts: in three months he had a battalion with five squadrons and a second battalion was under formation. Although no horses were available, the regiment was ordered into the camp near Strehlen, where it came under the command of Kurt Christoph Graf von Schwerin. In the First Silesian War the regiment fought in Silesia, Bohemia and Moravia. He was involved in the seven-week Siege of Olomouc.