Charles did not hasten to Alsace to settle matters in person, but pursued his intention of reducing Cologne to the archbishop's control, undoubtedly thinking that the base which would then be open to the archbishop's protector on the lower Rhine would facilitate his operations in the upper valleys. Meanwhile the Emperor Frederic had emphatically declared that he alone was the Defender of the Diocese, and that the unholy alliance between Robert and Charles was a menace to the empire. His letters to Charles exhorted him to abandon the enterprise and to accept mediation; those to the electors, princes, and cities of the empire urged them to defend Cologne against Burgundy until he himself arrived on the scene. There was a hot correspondence between all parties concerned, from which nothing resulted. Charles had various reasons for delay. There was trouble in other quarters of his domain. Flanders was in a state of ferment at his requisitions for money, and the Franche-Comté was on the point of making active resistance to the imposition of the _gabelle_. In view of all these complications, Charles decided to prolong his truce with Louis XI., to May 1, 1475. That monarch was well pleased to continue to pursue his own plans under cover of neutrality. The determination of the anti-Burgundian coalition in Germany to keep Charles within the limits of his own estates was a pleasant sight to the French king, and he felt that he could afford to wait. In June an edict was sent forth from Luxemburg, forbidding all owing allegiance to the Duke of Burgundy to have any commercial relations with the rebels of Cologne, or of Alsace, or with the cities of the _Basse Union_, and declaring the duke's intention to take the field at once, to reinstate the archbishop in his rightful see. This was a declaration of war and was speedily followed by the duke's advance to Maestricht, where he spent a few days in July, collecting a force which finally amounted to about twenty thousand men. On the 29th he sat down before Neuss, which had again emphatically refused entry to him and his troops. Three days the duke gave himself for the reduction of the town, but there he remained encamped for nearly a whole year! Neuss was resolved to resist to the last extremity, while Bonn, Andernach, and Cologne contributed their assistance by worrying and harassing the besiegers to the best of their ability. It was a period when Charles seemed to have only one sure ally, and that was Edward of England, whose own plans were forming for a mighty enterprise--no less than a new invasion of France.