The villainy was eminently successful. For forty years the republican party suppressed itself, and the government of the republic remained without question in the hands of the stadtholders of the House of Orange: Maurice, Frederick Henry, and William II. [Sidenote: =Government of Maurice, Frederick Henry, and William II., 1610–1650.=] Indeed, when this halcyon period came to an end, it was the ambition of the stadtholder, not the pride of the republicans, which was at fault. William II. had married a daughter of Charles I. of England, and undeterred by the fate of his father-in-law and the outbreak of the _Fronde_ he determined to effect a _coup d’état_ and turn the stadtholderate into a monarchy. Just before his death Frederick Henry had negotiated with Spain a treaty at Münster, finally ratified in January 1648, by which Spain and the United Provinces agreed to unite together in defence of the Spanish Netherlands against French aggression, on condition that Spain closed the Scheldt to trading vessels and acknowledged the independence of the republic. A more favourable treaty to the United Provinces cannot be imagined, for by it they obtained a barrier between their own territories and those of France, and secured the trade monopoly of Amsterdam. Yet William II. in his insensate ambition actually agreed to throw all these advantages away, and allow France to seize the Spanish Netherlands, in return for the consent of Mazarin to his projected revolution. [Sidenote: =Attempted coup d’état of William II., 1650.=] Having thus secured the neutrality of France he proceeded to put his scheme into execution. He was sure of the support of the army and of Zealand, and need not fear the opposition of any of the other provinces except Holland. His first business accordingly was to get up a quarrel between the states-general and the provincial estates of Holland about the disbandment of some troops, then, posing as the champion of the states-general, obtained from them authority to take measures for the preservation of the union, and to put pressure upon the estates of Holland. This was sufficient for him. After some negotiation, on the 30th of July 1650 he suddenly arrested six of the leading deputies of Holland, and directed his troops to march during the night upon Amsterdam. The city was saved by the merest accident. The night was dark and rainy, the troops lost their way. When day broke they were still outside the town. The alarm was given. Only one magistrate Cornelius Bicker von Swieten happened to be in the city, but it was enough. [Sidenote: =Death of William II., 1650.=] The gates were closed, the drawbridges raised, the militia called out, and Amsterdam was safe, and with Amsterdam the republic. A _coup d’état_ was now impossible. William saw he could only succeed by civil war and he did not dare to give the signal for that. For five months both sides eyed each other suspiciously, but neither dared to move.