By the Treaty of Blois (September 22), Milan was ensured to Louis XII., and, failing heirs-male, to Claude and her youthful bridegroom Charles.[64] But this agreement, like its predecessor, was not made to be observed. No sooner had d'Amboise obtained Louis' formal investiture from the Emperor (April 1505), than the betrothal of Claude to the Archduke was secretly annulled, and Francis of Angoulême took his place as her prospective husband. The death of Isabella the Catholic, and the struggle of Ferdinand and Philip for the Castilian Regency, removed all danger of any united effort between Spain and the Hapsburgs against France; and early in 1506 Louis' breach of faith was formally proclaimed and ratified by the States-General of Tours.[65] {51} Notwithstanding this rebuff, Maximilian had gained a very distinct advantage from peace with France. So long as the question of investiture was pending, Louis could not interfere in the affairs of the Empire, and Maximilian was free to profit by the turn of events. The death of George the Rich, Duke of Bavaria-Landshut (December 1, 1503), resulted in a disputed succession. In spite of a family agreement (Erbvertrag) which expressly nominated as his heirs Duke Albert IV. of Munich and his brother Wolfgang, the old Duke left his lands to his daughter Elizabeth, wife of Rupert, a younger son of the Elector Palatine. Both parties prepared to assert their rights, and Rupert, careless of the consequences, threw himself into Landshut, thus opening the war, and putting himself under the ban of the Empire.[66] The Estates refused allegiance to Albert, and called in Maximilian as mediator in the quarrel. The Emperor preferred to renounce his position of _tertius gaudens_, and to throw the whole weight of his support on Albert's side. Even had he not already, in 1497, recognized Albert's title, both justice and his own interests urged him to the Bavarian side. The Palatine House had ever been the foe of the Hapsburgs, and Duke Albert, as the Emperor's brother-in-law, would naturally seem the less dangerous of the two claimants. Maximilian at first offered Rupert a third of George's possessions, in the hope of averting hostilities; but, meeting with a curt refusal, he roused the forces of the Swabian League, and, assisted by Würtemberg, Brunswick and Hesse, took the field in person at the head of a considerable army. The sudden death of {52} Rupert (August 20, 1504), closely followed by that of his masculine wife Elizabeth, did not put an end to the war, the Elector continuing the struggle in the name of his grandsons. A fierce encounter took place near Regensburg between the Imperialists and a large body of Bohemian mercenaries in the Elector's service. Maximilian himself led the right wing to the charge, and drove the enemy back to their laager, which, after the example of Zizka, they had constructed from their baggage waggons. A desperate sally for the