The internal decay of Spain and the lassitude of her two feeble sovereigns, Philip III (1598-1621) and Philip IV (1621-1665), prevented her from rendering any material assistance to Austria, where the other branch of the Hapsburgs, descendants of Charles V's brother Ferdinand, were reduced to struggle for their very existence. Ferdinand and his immediate successor as Emperor of Germany had kept the religious peace carefully, and Germany had prospered. But then came new emperors who repudiated their methods--Ferdinand had been deemed by the Church little better than a Protestant. In 1608 the Protestant princes, becoming suspicious, formed a league for mutual defence. The Catholics under Maximilian of Bavaria formed an answering league in 1609. They almost came to open war that year over a disputed succession in one of the smaller duchies, the Protestants appealing to Holland for help and the Catholics to Spain. Fortunately the terrible example of the civil wars they had seen in France, held them back for a time. But always there were arising new grounds for quarrel. THE THIRTY YEARS' WAR In 1618 the actual war began. A new leader, Ferdinand II, young and intensely Catholic, had risen to guide the Hapsburg fortunes in Austria, had successfully forced that land to resume the old religion, and now aimed to do the same in Bohemia. The Bohemians, famed fanatics of the unforgotten Hussite wars, broke into open rebellion, threw Ferdinand's ministers through a window, and so roused the war that ruined Germany.[7] Ferdinand became Emperor of Germany the next year (1619), and called the Catholic league to his aid in Bohemia. The rebels elected as king one of the German electors, a son-in-law of the King of England, and head of the Protestant league. Slowly, unwillingly, the various German states, and the surrounding countries also, found themselves dragged into the struggle. At first Emperor Ferdinand was successful, Bohemia was completely subdued and made Catholic, as Austria had been. A great general and shrewd contriver, Wallenstein, rose to the Emperor's aid and laid Germany prostrate at his feet. For a moment the Hapsburgs seemed as all-powerful as in the proudest days of Charles V. But his own coreligionists turned against Ferdinand. The princes of the Catholic league grew frightened; he was indeed crushing Protestantism, but he was trampling on their rights as well. They fell away from his alliance. Richelieu, also dreading the Hapsburg aggrandizement, brought France to take part in the war. Sweden's hero-king Gustavus Adolphus invaded Germany to defend the Protestant faith. He won splendid victories, but at last fell in his supreme battle at Luetzen, from which Wallenstein's troops fled defeated (1632).[8]