After William IV's death in 1751, his infant son was duly appointed "stadtholder" under the regency of his mother. The misgovernment of this regency caused much resentment, which issued in 1780 in the Patriot movement, seeking to permanently limit the powers of the Stadholderate. The Patriots first took over many city councils, then the States of the province of Holland, and ultimately raised civil militias to defend their position against Orangist partisans, bringing the country to the brink of civil war. Through Prussian military intervention in 1787, Prince William V of Orange was able to suppress this opposition, and many leaders of the Patriot movement went into exile in France. The stadtholderate was strengthened with the Act of Guarantee (1788).