or William of Orange (William I, prince of Orange), 1533–84, Dutch statesman, principal founder of Dutch independence.
A descendant of the Ottonian line of Nassau, he was born at Dillenburg, near Wiesbaden, Germany, of Protestant parents. After inheriting (1544) the holdings of the branch of the Nassau family in the Low Countries and the principality of Orange in S France, William was reared a Roman Catholic at the insistence of Holy Roman Emperor Charles V, whose favorite page he became. In 1555 he was made stadtholder of Holland, Zeeland, and Utrecht.
William ably served Philip II of Spain as a diplomat, particularly in the making of the Treaty of Cateau-Cambrésis (1559), but Philip's encroachments on the liberties of the Netherlands and the introduction of the Spanish Inquisition by Cardinal Granvelle led William to turn against the king. In 1563, with the help of counts Egmont and Hoorn, he succeeded in obtaining the removal of Granvelle, but under the regency of Margaret of Parma disorders grew in the Netherlands.
In 1566 the party of the Gueux was organized with William's connivance, and when Alba was sent to the Netherlands to quell the rebels, William withdrew to Germany. When he refused Alba's summons to appear before a tribunal, his property was confiscated. William and his brother Louis of Nassau raised an army to drive the Spanish out of the Netherlands. They at first met defeat, but in 1576 the provinces of the Netherlands, taking advantage of the mutiny of the Spanish army under John of Austria, united under William's leadership in the Pacification of Ghent for the purpose of expelling the Spanish. In 1573, chiefly for the sake of policy, William had become a Calvinist.
The struggle with Spain continued. The Union of Utrecht (1579) proclaimed the virtual independence of the northern provinces, of which William was the uncrowned ruler, but the victories of the Spaniards under Alessandro Farnese forced William to seek French support by offering (1580) the rule over the Netherlands to Francis, duke of Alençon and Anjou. Philip II denounced William as a traitor, and a high price was set on his head in 1581.
William replied with his famous Apologia, in which he not only sought to vindicate his own conduct, but hurled violent accusations at the Spanish king. In the same year the representatives of Brabant, Flanders, Utrecht, Gelderland, Holland, and Zeeland solemnly declared Philip deposed from sovereignty over those provinces. William's support of the unpopular Francis resulted in the wane of William's own popularity during his last years. He was assassinated at Delft by a French Catholic fanatic, while the struggle against Spain was still in a critical stage.
William married four times. His first wife was Anne of Egmont and Buren (d. 1558); in 1561 he married Anne, daughter of Elector Maurice of Saxony, in spite of the opposition of Philip II and of Anne's parents; in 1575, two years before Anne's death, he married Charlotte de Bourbon, a French princess and a runaway nun, after securing the approval of several Protestant divines; in 1583 he married Louise de Coligny, daughter of Admiral Coligny. From the first marriage Prince Philip William of Orange (d. 1616) was born; from the second and fourth marriages issued William's successors as stadtholders—Maurice of Nassau and Frederick Henry.