Sigismund’s letter to Charles is casual in tone and obscure in phraseology. A statement presented somewhat later to the emperor by the Basse Union is more precise in the justification offered for the events and in the grievances rehearsed.[10] That is, Sigismund treats the transaction as a purely financial one, naturally completed between him and his creditor by the offer to liquidate his debt. The plea made by the Alsatians and their friends is, that Charles had failed to keep his solemn engagements and that his appointed lieutenant had been peculiarly odious and had broken the laws of God and man, and that the mercenaries employed by him, the Burgundians, Lombardians, and their fellows, had pitilessly ravaged the county of Ferrette, the Sundgau, and the diocese of Basel. The charges are itemised.[11]
“All this, well-known to the Duke of Burgundy, has neither been checked nor punished by him. In consequence, our gracious Seigneur of Austria has been obliged to restore the land and people to his sovereignty and that of the House of Austria, which he has done with God’s aid to prevent the complete annihilation and total destruction of land and people.”
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-Comte 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.