A Catholic League was at once formed under Maximilian. It was composed of a large number of bishops and abbots, who believed that the princes of the Union wished to annex their territories. Maximilian's ability gave it a unity of action which the Union never possessed. It, too, was constituted for self-defence, but whether that word was to include the resumption of the lands lost since the Convention of Passau was a question probably left for circumstances to decide. [Sidenote: § 15. Revolutionary tendencies of the Union.] Whatever the majority of the princes of the Union may have meant, there can be no doubt that Christian of Anhalt meant aggression. He believed that the safety of Protestantism could not be secured without the overthrow of the German branch of the House of Austria, and he was sanguine enough to fancy that an act which would call up all Catholic Europe in arms against him was a very easy undertaking. [Sidenote: 1609. § 16. The succession of Cleves.] Scarcely had the Union been formed when events occurred which almost dragged Germany into war. In the spring of 1609 the Duke of Cleves died. The Elector of Brandenburg and the son of the Duke of Neuburg laid claim to the succession. On the plea that the Emperor had the right to settle the point, a Catholic army advanced to take possession of the country. The two pretenders, both of them Lutherans, made common cause against the invaders. [Sidenote: 1610.] Henry IV. of France found in the dispute a pretext for commencing his long-meditated attack upon Spain and her allies. But his life was cut short by an assassin, and his widow only thought of sending a small French force to join the English and the Dutch in maintaining the claims of the two princes, who were ready to unite for a time against a third party. [Sidenote: 1613. § 17. The box on the ear.] It was not easy to bring the princes to an arrangement for the future. One day the young Prince of Neuburg proposed what seemed to him an excellent way out of the difficulty. 'He was ready,' he said, 'to marry the Elector's daughter, if only he might have the territory.' Enraged at the impudence of the proposal, the Elector raised his hand and boxed his young rival's ears. The blow had unexpected consequences. The injured prince renounced his Protestantism, and invoked, as a good Catholic, the aid of Spain and the League. The Elector passed from Lutheranism to Calvinism, and took a more active part than before in the affairs of the Union. That immediate war in Germany did not result from the quarrel is probably the strongest possible evidence of the reluctance of the German people to break the peace. [Sidenote: 1612. § 18. John George, Elector of Saxony.]