He first gained military experience in the Italian Wars, and so distinguished himself at the battle of Ceresole (1544) that Louis de Bourbon, still comte d'Enghien at that time, knighted him on the battlefield. In 1547 he was made inspector-general of the infantry, and commanded the French troops sent to Scotland to defend the rights of Mary, Queen of Scots (until 1559, queen-consort of France). When war broke out again in Italy, he returned, marching to Parma and getting trapped in the city when it soon afterwards came under siege. Taken prisoner during a sortie, he was taken to the castle of Milan, where he remained until the treaty of Vaucelles in 1556.