He left Bavaria on the death of Charles VII, and after brief service under Frederick the Great joined Marshal Saxe in the Netherlands and was created a field-marshal of the French army. He distinguished himself especially at Lauffeld, Rocoux and Maastricht. On the outbreak of the Seven Years' War (1756) he was appointed lieutenant-general, and although he showed greater ability than any of his fellow-commanders and was admired by his soldiers, he fell a victim to court intrigues, professional jealousy and hostile criticism. He resigned his commission in 1760 and accepted an appointment as field-marshal from Frederick V of Denmark-Norway, being charged in 1762 with the reorganization of the Danish army.