of Vincenzo II, the last male of the Mantuan Gonzaga line. Several candidates contended the succession. The emperor supported Charles Emmanuel I, Duke of Savoy, whereas France and Venice supported Charles Gonzaga, duc de Nevers. In 1629 an Imperial army beleaguered and took Mantua, but the troops were soon recalled to Germany to fight in the Thirty Years' War (1618–1648). France therefore prevailed and the duc de Nevers acceded to the ducal throne of Mantua. Claude de Mesmes did not hesitate to spend money to enhance the prestige of France and his king: in October 1628 he celebrated the capture of La Rochelle by feasts and firework in Venice. After Venice he was sent to Rome, Mantua, Florence and Turin. Treaty of Stuhmsdorf During the later phase of the Thirty Years' War, France was allied with Sweden. Richelieu feared that the Polish menace on their left flank would distract the Swedes from fighting the emperor in Germany. The Polish-Swedish war of 1626–1629 had ended with the truce signed at Altmark after the Swedish defeat at Honigfelde. This truce was to expire in July 1635 and the new Polish king, Władysław IV Vasa, seemed poised to resume the war. To ensure a timely renewal of the truce, Richelieu sent Claude de Mesmes to Poland as a mediator. The French delegation left Paris on 11 July 1634. Claude de Mesmes was accompanied among others by his secretary , who kept a diary. Avoiding war-torn Germany, the delegation travelled via Denmark and Sweden. On the way Claude de Mesmes stopped in Copenhagen in 1634 to represent France at the wedding of crown prince Christian with Magdalene Sibylle of Saxony. While in Copenhagen they received the news of the Swedish defeat at Nördlingen on 27 August (old style), which further weakened Sweden's position. From Denmark the delegation travelled to Sweden where they passed the winter and met officials in Stockholm. They arrived in Dantzig (now Gdańsk) on 17 May 1635 and proceeded to Marienburg (now Malbork) where they took up quarters in the castle. The French delegation arrived late. The negotiations had started on 24 January in the church of the small town of Holland (now Pasłęk) in Ducal Prussia. The Brandenburger delegation, which was mediating, stayed in that town. The Polish delegation (in fact the one representing the Polish–Lithuanian Commonwealth) stayed at Mohrungen (now Morąg). Brandenburg was represented by Siegmund of Brandenburg, ,