In 1695, he took up his residence in
Siegen. In the same year, the city fell victim to a great fire, which burned 350 buildings, two churches and the Nassau Court, the headquarters of the ruling family. His father began building a new castle in Siegen as the new family home in 1696. From 17 December 1699 to 2 March 1707, William Hyacinth was the ruler of
Nassau-Siegen. He was hoping to inherit much more than his father's principality of Nassau-Siegen, since he was one of the nearest male relatives of the childless King
William III of England, and thus a potential heir to William's extensive lands in Germany and the
Dutch Republic. However, William III left his possessions by will to John William Friso of
Nassau-Dietz. William Hyacinth later used the title of Prince of Orange in Brabant. He did not even inherit all of his father's wealth. His father had remarried with Isabella Clara du Puget de la Serre and had had seven surviving children with her. In his will, he left her a
bequest of 1100
taler per year. Her two sons each received 500 taler per year and her five daughters 200 taler each. William Hyacinth challenged this will before the
Imperial Supreme Court, however, he lost his case in 1702. In the same year William III died in England. William Hyacinth traveled to Paris to secure the support of France with regard to his rights of inheritance. Other claimants were King
Frederick I of Prussia and
John William Friso of Nassau-Dietz, who was designated as the sole heir in the testament of King William III of
England. King
Louis XIV, however, showed little interest in supporting a prince without military power base. William Hyacinth then travelled to the
principality of Orange and announced there that he had seized the principality. Louis XIV declared that the Prince
Henri Jules of Condé was the rightful heir to the principality of Orange and occupied it militarily. Henri Jules transferred the principality to France. In the
Treaty of Utrecht of 1713, the lands of the principality were definitively awarded to France. His lavish court, with which he wanted to underscore his claim to the inheritance of Orange, his journeys and gifts cost far more than his income from the Duchy of Nassau-Siegen could bear. William Hyacinth was consequently indebted to the bankers De Rhön and Schonemann from Frankfurt, pledging of the villages
Wilnsdorf and
Wilgersdorf for . He increased taxes across the country to intolerable levels. Another source of income were excessive fines, which further damaged his reputation in his country. His quick temper and ambition were feared in their own family. When his brother (and successor)
Frederick William Adolf expressed his displeasure, William Hyacinth directed the guns of his castle on his brother's castle in order to demonstrate his power. Frederick William Adolf then sued his brother in the assembly of the
Westphalian Circle. When William Hyacinth visited the court in Vienna in 1705, to raise support for his inheritance claim, Siegen was occupied by troops from Nassau and Prussia. The people revolted and plundered and disarmed William Hyacinth's castle. The number of complaints about his conduct continued to increase. On 15 July 1706, Siegen was again occupied, this time by troops from
County Palatine of Neuburg and Prussia, at the request of the
Aulic Council. William Hyacinth's Chancellor, de Colomba, who had played a major rôle in William Hyacinth's tyranny, was arrested and on 20 December 1710 exiled from the German Empire for life. William Hyacinth himself fled to Hadamar, to his cousin
Prince Francis Alexander, the last ruler of
Nassau-Hadamar. The revolts against his reign of terror continued. On 29 March 1707 William Hyacinth had Friedrich Flender von der Hardt, a suspected leader of the insurgents, beheaded without any form of trial. Emperor
Joseph I used this occasion to deprive William Hyacinth of his principality. It was temporarily administered by two imperial councillors and then passed to
Frederick William Adolf. In 1713, France withdrew William Hyacinth's French title of
Count of Chalon. William Hyacinth was awarded an annual pension of 4000 talers. The remaining assets were used to pay the pensions of his stepmother and her siblings, his creditors and a debt of honor to the family of Friedrich Flender. William Hyacinth complained to the emperor and to the
Diet of Regensburg, however, neither complaint met with success. == Marriages and issue ==