William I, Prince of Orange (b. April 24, 1533, Dillenburg, County of Nassau–d. July 10, 1584, Delft, Spanish Netherlands), also widely known as William the Silent or William of Orange, was the main leader of the Dutch revolt against the Spanish Habsburgs that set off the Eighty Years' War (1568–1648) and resulted in the formal independence of the United Provinces in 1581. He was born in the House of Nassau as Count of Nassau-Dillenburg. He became Prince of Orange in 1544 and is the ancestor of the monarchy of the Netherlands. Within the Netherlands he is also known as Father of the Fatherland.
A wealthy nobleman, William originally served the Habsburgs as a member of the court of Margaret of Parma, governor of the Spanish Netherlands. Unhappy with the centralisation of political power away from the local estates and with the Spanish persecution of Dutch Protestants, William joined the Dutch uprising and turned against his former masters. The most influential and politically capable of the rebels, he led the Dutch to several successes in the fight against the Spanish. Declared an outlaw by the Spanish king in 1580, he was assassinated by Balthasar Gérard in Delft in 1584.