The news of the capture of Brill and Flushing stirred him to sudden action.

He had collected only a small body of men, but, with characteristic impetuosity he now led these across the frontier, and, before Alva was aware of his presence in Hainault, had captured by surprise Valenciennes and Mons (May 24).

It was a rash move, for no sooner did the news reach the governor-general than he sent his son, Don Frederick of Toledo, at the head of a powerful force to expel the invader.

Don Frederick quickly made himself master of Valenciennes and then proceeded (June 3) to lay siege to Mons, where Lewis, in hopes that relief would reach him, prepared for an obstinate defence.

These hopes were not without foundation, for he knew that, beyond the Rhine, Orange with a considerable army was on the point of entering the Netherlands from the east, and that the Huguenot leader, Genlis, was leading another force from France to his succour.