Maurice of Nassau (in Dutch Maurits van Nassau) (14 November 1567–23 April 1625), Prince of Orange (1618–1625), son of William the Silent and Princess Anna of Saxony, was born at the castle of Dillenburg. He was named for his maternal grandfather, the Elector Maurice of Saxony .

Maurice never married but was the father of illegitimate children by Margaretha van Mechelen and Anna van de Kelder. He was raised in Dillenburg by his uncle Johan_of_Nassau (Jan the Old). Together with his cousin Willem Lodewijk he studied in Heidelberg and later with his brother Filips in Leiden where he met Simon Stevin. The States of Holland and Zeeland paid for his studies, as their father had run into financial problems after spending his entire fortune in the early stages of the Dutch revolt. When his father was murdered in Delft in 1584, he took over as stadtholder (Stadhouder), though this title was not inheritable. He became stadtholder of Holland and Zeeland in 1585, of Gelderland, Overijssel and Utrecht in 1590 and of Groningen and Drenthe in 1620 (following the death of Willem Lodewijk, who had been Stadtholder there and in Friesland).

He was appointed captain-general of the army in 1587, bypassing the Earl of Leicester, who returned to England on hearing this news.

The Prince organised the rebellion against Spain into a coherent, successful revolt. He reorganised the army together with Willem Lodewijk, studied military history, strategy and tactics, mathematics and astronomy, and proved himself to be among the best strategists of his age. Paying special attention to the siege theories of Simon Stevin, he took valuable key fortresses and towns: Breda in 1590, Steenwijk in 1592, and Geertruidenberg in 1593.

His victories in the cavalry battles at Turnhout (1597) and at Nieuwpoort 1600 earned him military fame and acknowledgment throughout Europe. Despite these successes, the House of Orange did not attain great respect among European Royalty, as the Stadtholdership was not inheritable.

Maurice and Oldenbarnevelt

Maurice started out as the protégé of Landsadvocaat (Country Advocate, a kind of secretary) Johan van Oldenbarnevelt. But gradually tensions rose between these two great men. Against Maurice's advice, and despite his protests, Van Oldenbarnevelt decided to sign the Twelve Year Truce with Spain, which lasted from 1609 - 1621. The required funds to maintain the army and navy, and the general course of the war were other topics of constant struggle.

With the religious troubles between Gomarists (Calvinist) and Arminians, the struggle between Van Oldenbarnevelt and Maurice reached a climax. Van Oldenbarnevelt was decapitated despite numerous requests for mercy.

Maurice urged his brother Frederick Henry to marry in order to preserve the dynasty.

In 1621 the war resumed, and the Spanish, led by Ambrosio Spinola, had notable successes, including the recapture of Breda in 1625. Maurice died shortly thereafter.