A notable thesis propagated by Trevor-Roper was the "general crisis of the 17th century". He argued that the middle years of the 17th century in Western Europe saw a widespread break-down in politics, economics and society caused by demographic, social, religious, economic and political problems. In this "general crisis,” various events, such as the English Civil War, the "Fronde" in France, the climax of the Thirty Years' War in Germany, troubles in the Netherlands, and revolts against the Spanish Crown in Portugal, Naples and Catalonia, were all manifestations of the same problems. The most important causes of the “general crisis” in Trevor-Roper's opinion were conflicts between “Court” and “Country”; that is between the increasingly powerful centralizing, bureaucratic, sovereign princely states, represented by the Court, and the traditional, regional, land-based aristocracy and gentry, representing the country. In addition, he said that the religious and intellectual changes introduced by the Reformation and the Renaissance were important secondary causes of the "general crisis."