The cardinal listened to his advice, and determined to bring about a union between the two armies of the confederation.

In the meantime a conference was going on at Munster between the representatives of the various conflicting powers, but each put forward such exorbitant demands that no progress was made.
The Duke of Bavaria, indignant at the small support that Austria had given him, was playing off France against the latter power.

Mazarin was persuaded that he was only waiting for an opportunity to desert the Imperialist cause, and therefore ordered Turenne not to cross the Rhine, as the duke had promised that he would remain neutral unless the French advanced into Germany, when the feelings of his subjects might force him to take the field again on the side of Austria.
Turenne was therefore ordered to besiege Luxembourg.

The marshal, however, had no belief in the Bavarian promises, and on arriving on the Rhine early in April, and seeing that were he to march with his army away to Luxembourg the cause of France and Germany would be lost, he continued to make various excuses for not moving, until the Duke of Bavaria, having obtained many concessions from Austria, threw off the mask, and marching with his army joined that of the emperor in Franconia.

Thus the whole Imperial forces were posted between the French and the Swedes.
Turenne saw that his only hope of success would be to effect a juncture with the Swedes, and wrote to the cardinal to that effect; then, without waiting for an answer, he set his army in motion.