The conditions, accordingly, upon which he offered to adopt the neutrality toward Bavaria were severe, and suited to these views. He required of the whole League a full and entire cessation from all hostilities; the recall of their troops from the imperial army, from the conquered towns, and from all the Protestant countries; the reduction of their military force; the exclusion of the imperial armies from their territories, and from supplies either of men, provisions, or ammunition. Hard as the conditions were, which the victor thus imposed upon the vanquished, the French mediator flattered himself he should be able to induce the Elector of Bavaria to accept them. In order to give time for an accommodation, Gustavus had agreed to a cessation of hostilities for a fortnight. But at the very time when this monarch was receiving from the French agents repeated assurances of the favorable progress of the negotiation, an intercepted letter from the Elector to Pappenheim, the imperial general in Westphalia, revealed the perfidy of that prince, as having no other object in view by the whole negotiation than to gain time for his measures of defence. Far from intending to fetter his military operations by a truce with Sweden, the artful prince hastened his preparations, and employed the leisure which his enemy afforded him, in making the most active dispositions for resistance. The negotiation accordingly failed, and served only to increase the animosity of the Bavarians and the Swedes. Tilly's augmented force, with which he threatened to overrun Franconia, urgently required the king's presence in that circle; but it was necessary to expel previously the Spaniards from the Rhine, and to cut off their means of invading Germany from the Netherlands. With this view, Gustavus Adolphus had made an offer of neutrality to the Elector of Treves, Philip von Zeltern, on condition that the fortress of Hermanstein should be delivered up to him, and a free passage granted to his troops through Coblentz. But unwillingly as the Elector had beheld the Spaniards within his territories, he was still less disposed to commit his estates to the suspicious protection of a heretic, and to make the Swedish conqueror master of his destinies. Too weak to maintain his independence between two such powerful competitors, he took refuge in the protection of France. With his usual prudence, Richelieu profited by the embarrassments of this prince to augment the power of France, and to gain for her an important ally on the German frontier. A numerous French army was dispatched to protect the territory of Treves, and a French garrison was received into Ehrenbreitstein. But the object which had moved the Elector to this bold step was not completely gained, for the offended pride of Gustavus Adolphus was not appeased till he had obtained a free passage for his troops through Treves.