One day in March 1631, a dust-covered horseman appeared before the gates of Besançon. To the shouted questions of the sentries, he replied that he was a follower of Gaston, duc d'Orléans, brother of King Louis XIII of France, and he had an urgent message for the rulers of the city. Brought before the hastily assembled city council, he announced that his master was requesting sanctuary in Besançon. The loser in a bitter power struggle with Cardinal Richelieu, Gaston was now fleeing France in rebellion against his brother.

The duc d'Orléans's messenger arrived at a time of acute anxiety in Franche-Comté. All around the province, Europe was plunged into violence and disorder. For the past decade, the Holy Roman Empire had been embroiled in a savage religious civil war. In the Low Countries, the Spanish monarchy, sovereign ruler of Franche-Comté, had renewed its seemingly endless struggle with the Dutch. Most ominously, tensions between Bourbon France and the Habsburg powers were rapidly escalating to the point where open war appeared ever more likely. Thus far, Franche-Comté itself had managed to avoid being drawn into these conflicts only because of a long-standing treaty establishing a state of neutrality between the two Burgundys, the French duchy and the Spanish county.

Gaston's request for sanctuary therefore presented the magistrates of Besançon with a quandary. They feared that by granting the rebel duke sanctuary in their city, they would hand France an excuse to abrogate the treaty.