As Guise passed through Wassy-sur-Blaise on his way to Paris (1 March 1562), a massacre of Protestants took place. It is not known to what extent he was responsible for this, but the Massacre of Vassy kindled open military conflict in the French Wars of Religion. The siege of Bourges in September was the opening episode, then Rouen was retaken from the Protestants by Guise after a month's siege (October); the Battle of Dreux (19 December), at which Montmorency was taken prisoner and Saint-André slain, was in the end turned by Guise to the advantage of the Catholic cause, and Condé, leader of the Huguenots, was taken prisoner.