Some troops were levied and assembled.

Couriers were sent to recall the duke of Guise and his army from Italy: and the French, having recovered from their first panic, put themselves in a posture of defence.

Philip, after taking Ham and Catelet, found the season so far advanced, that he could attempt no other enterprise: he broke up his camp, and retired to winter quarters.
But the vigilant activity of Guise, not satisfied with securing the frontiers, prompted him, in the depth of winter, to plan an enterprise which France, during her greatest successes, had always regarded as impracticable, and had never thought of undertaking.

Calais was in that age deemed an impregnable fortress; and as it was known to be the favorite of the English nation, by whom it could easily be succored, the recovery of that place by France was considered as totally desperate.
But Coligny had remarked, that as the town of Calais was surrounded with marshes, which during the winter were impassable, except over a dike guarded by two castles, St.Agatha and Newnam Bridge, the English were of late accustomed, on account of the lowness of their finances, to dismiss a great part of the garrison at the end of autumn, and to recall them in the spring, at which time alone they judged their attendance necessary.

On this circumstance he had founded the design of making a sudden attack on Calais; he had caused the place to be secretly viewed by some engineers; and a plan of the whole enterprise being found among his papers, it served, though he himself was made prisoner on the taking of St.Quintin, to suggest the project of that undertaking, and to direct the measures of the duke of Guise.
Several bodies of troops defiled towards the frontiers on various pretences; and the whole, being suddenly assembled, formed an army, with which Guise made an unexpected march towards Calais.