Guebriant left the Hessians to defend their conquests on the Lower Rhine against Hatzfeldt, and advanced towards Thuringia, as if to second the operations of Torstensohn in Saxony. But instead of joining the Swedes, he soon hurried back to the Rhine and the Maine, from which he seemed to think he had removed farther than was expedient. But being anticipated in the Margraviate of Baden, by the Bavarians under Mercy and John de Werth, he was obliged to wander about for several weeks, exposed, without shelter, to the inclemency of the winter, and generally encamping upon the snow, till he found a miserable refuge in Breisgau. He at last took the field; and, in the next summer, by keeping the Bavarian army employed in Suabia, prevented it from relieving Thionville, which was besieged by Conde. But the superiority of the enemy soon drove him back to Alsace, where he awaited a reinforcement. The death of Cardinal Richelieu took place in November, 1642, and the subsequent change in the throne and in the ministry, occasioned by the death of Louis XIII., had for some time withdrawn the attention of France from the German war, and was the cause of the inaction of its troops in the field. But Mazarin, the inheritor, not only of Richelieu's power, but also of his principles and his projects, followed out with renewed zeal the plans of his predecessor, though the French subject was destined to pay dearly enough for the political greatness of his country. The main strength of its armies, which Richelieu had employed against the Spaniards, was by Mazarin directed against the Emperor; and the anxiety with which he carried on the war in Germany, proved the sincerity of his opinion, that the German army was the right arm of his king, and a wall of safety around France. Immediately upon the surrender of Thionville, he sent a considerable reinforcement to Field-Marshal Guebriant in Alsace; and to encourage the troops to bear the fatigues of the German war, the celebrated victor of Rocroi, the Duke of Enghien, afterwards Prince of Conde, was placed at their head. Guebriant now felt himself strong enough to appear again in Germany with repute. He hastened across the Rhine with the view of procuring better winter quarters in Suabia, and actually made himself master of Rothweil, where a Bavarian magazine fell into his hands. But the place was too dearly purchased for its worth, and was again lost even more speedily than it had been taken. Guebriant received a wound in the arm, which the surgeon's unskilfulness rendered mortal, and the extent of his loss was felt on the very day of his death.