The Archdukes died childless and the Habsburg Netherlands returned by default to the King of Spain. When Maurice died he was succeeded by his brother Frederick-Henry, an accomplished warrior himself. The truce ended and Frederick-Henry won great victories. He was Stadtholder off all Provinces except Groningen and Frisia. There the ruling Counts of Nassau-Dietz, descendants of his Uncle John, were Stadtholders. During the rule of his son Stadtholder William II, the Peace Treaties of Westphalia came about in 1648, effectively ending the conflict with Spain, and the parallel Thirty Years war in Germany. The Republic was now recognised by the European powers as an independent Nation, even independent of the Empire, although the Emperor would only recognise that in 1703. Upon the death of Prince William II of Orange, the office of Stadtholder was suspended in all but two of the Dutch provinces, Groningen and Frisia being administered by Stadtholders of the collateral Nassau-Dietz branch, descendants of William the Silentís brother John of Nassau. In the rest of the Republic a semi-aristocratic oligarchy of "Regents" came to power. The heir to the Orange name, Prince William III was underage at the time. In 1672, when the Republic came under attack from virtually all of its neighbours in a coalition led by France and the Stuart monarchs of England, the Dutch rallied to the side of William III who was made hereditary Stadtholder and saved the Republic.