The Treaty of Arras resulted in the reconquest, without bloodshed, of the southern part of Belgium; it provoked a rupture between Catholics and Protestants, the separation of the Walloons and the Flemings, and crushed the plans of the Prince of Orange. Henceforth it would be no longer possible to unite the whole of Belgium against Spanish rule. William the Silent replied to the Treaty of Arras by the so-called Union of Utrecht (1579), whereby the northern provinces of the Netherlands united themselves in the common struggle and decided to carry on the revolt to ultimate victory. Slowly, but surely, the secession of Belgium from Holland was in progress. The Prince of Orange, infuriated by the blow inflicted on his policy, now proclaimed the forfeiture by Philip II of the sovereignty of the Netherlands and offered the crown to the Duke of Anjou, brother of the French King Henry III (1584). He himself received the title of governor of Holland and Zeeland and remained the real leader of the union. Philip II replied by declaring the Prince an outlaw and putting a price on his head. Such an appeal to murder was common in the sixteenth century and was even supported by the teaching of many theorists; today it seems cruel and opposed to every principle of civilization. A man fanatical enough to fulfil the desire of the Spanish King was soon found. Balthazar Gérard treacherously assassinated the Prince of Orange at Delft, in 1584. So died the leader of the revolt of the Netherlands against Spain. He did not succeed in uniting the whole of Belgium against Philip II, but he initiated the United Provinces of Holland. The Dutch are right, therefore, in calling him the “Father of the Fatherland.” Meanwhile, supported by the Catholic provinces, Alexander Farnese had successively reconquered all the Belgian cities and won an imperishable fame by the siege and conquest of Antwerp. Only Ostend resisted and could not be taken. It seemed now to be the turn of the north, and already the United Provinces were threatened with invasion, when the unwise policy of Philip II suddenly stopped the advance. The lonely autocrat of the Escurial had planned the invasion of England and the conquest of the throne of France, where Henry IV, a Protestant but the legitimate heir, was at war with the Catholic League. To these plans he sacrificed all the resources of Spain from 1587 to 1592 and forced Farnese to suspend his campaign in Flanders, to assist in the transport of troops for the invasion of England, and to aid with his army the League in France. Both enterprises failed utterly, the invasion of England by the defeat of the Spanish Armada, the conquest of the French throne by the final rally of the country to the support of Henry IV.