Almost a decade of peace ended with the outbreak of the Seven Years' War in Europe. Crillon resumed active service with the Army of Germany (Reichsarmee) in 1757, when he first served in a separate corps commanded by the Prince of Soubise on the frontiers of Saxony and then joined the French Grand Army. He defended the city of Weißenfels in October 1757, commanding four imperial battalions and 17 companies of French grenadiers. He executed a retreat, but on 5 November he was injured when he had his horse shot out from under him at the Battle of Rossbach.