Frederick's sudden flight broke up the conference; but Charles was far from relinquishing his plans.

To win the mastery of the whole Rhine valley was the first step in their realization, and at the opening of 1474 he undertook the siege of Neuss, whose reduction meant that of Koeln and of the central district which broke his sway along it.

But vast as were the new dreams of ambition which thus opened before Charles, he had given no open sign of his change of purpose.
Lewis watched his progress on the Rhine almost as jealously as his attitude on the Somme; and the friendship of England was still of the highest value as a check on any attempt of France to interrupt his plans.
With this view the Duke maintained his relations with England and fed Edward's hopes of a joint invasion.

In the summer of 1474, on the eve of his march upon the Rhine, he concluded a treaty for an attack on France which was to open on his return after the capture of Neuss.

Edward was to recover Normandy and Aquitaine as well as his "kingdom of France"; Champagne and Bar were to be the prizes of Charles.