Henry IV had for some time been making preparations for war, and he was at the moment irritated by the protection given by the archdukes to the runaway Princess of Conde, who had fled to Brussels.

He had succeeded in persuading the States to send an auxiliary force into Germany to assist the French army of invasion in the spring of 1610, when just as the king was on the point of leaving Paris to go to the front he was assassinated on May 14.

This event put an end to the expedition, for the regent, Marie de' Medici, was friendly to Austria.
The States nevertheless did not feel disposed to leave Leopold in possession of Juelich.

Maurice led an army into the duchy and laid siege to the town.

It capitulated on September 1.