William I. (Frederik Wilhelm), first king of the Netherlands, grand duke of Luxemburg, born at the Hague, Aug. 24, 1772, died in Berlin, Dec. 12, 1843. His mother was a niece of Frederick the Great, and his father was the last stadtholder of the republic, as William V. As prince of Orange he had command of the Dutch army till 1795, when, the country being conquered by France, he joined his father at Hampton court, and subsequently went to Berlin. In 1802 he received from his father the principality of Fulda and other territories which had been given to him in compensation for the Netherlands, but lost them in 1806 for refusing to join the Rhenish confederation. His father died in the same year. He became a Prussian general, fell into the hands of the French at the battle of Jena, but was released, and served under the Austrians at Wagram in 1809. On the downfall of Napoleon he was, in conformity to the resolutions of the congress of Vienna, declared king of the Netherlands by an assembly of notables as William I., March 16, 1815, under a limited constitution, and with Belgium included in the new kingdom; and at the same time he exchanged his German possessions for the grand duchy of Luxemburg. The Belgians having established their independence with the aid of France (1830-'32), he stubbornly refused to acknowledge it, but was finally in 1839 obliged to yield.
The financial embarrassments of the country, and his relations with the Catholic and Belgian countess Henriette d'Oultremont, made him unpopular. On Oct. 7, 1840, he abdicated in favor of his eldest son William II., and retired to Berlin, where in 1841 he married the countess, his first wife, a daughter of Frederick William II. of Prussia, having died in 1837. He left an immense fortune. His second son, Prince Frederick, born Feb. 28,1797, became a field marshal, admiral, and colonel general in the Prussian service. He married the princess Louisa, daughter of Frederick William III.