of supplies forced him to retreat into Alsace where he set up winter quarters at Saverne. For 1636, Ferdinand of Hungary had convinced the Cardinal-Infante to invade France from the north in an attempt to end the war. Gallas was ordered to lead a separate southern invasion into Burgundy to support Spain. Despite Gallas' reluctance to initiate offensive campaigns, he collected his troops in Breisach and marched via the Belfort Gap into the Franche-Comté. French troops had invaded this Habsburg territory in May and were besieging the capital Dole. Gallas sent his vanguard under Guillaume de Lamboy and the Duke of Lorraine ahead; they relieved Dole in August. His main force encamped at Champlitte where it was confronted by a French army under Bernhard of Saxe-Weimar and La Valette in September. Unwilling to attack the French head-on, Gallas broke up his camp after several weeks and marched on Dijon. After capturing the castle of Mirebeau-sur-Bèze on 24 October, he was again hesitant to advance further and decided to lay siege to Saint-Jean-de-Losne to secure its strategic bridge for supplies or a possible retreat. However, the small town resisted all Imperial attacks until French reinforcements and heavy rain forced Gallas to abandon the siege and the overall invasion in early November. After being sent to northern Germany with his army in 1637, Gallas was more successful at stopping the advance of the Swedish general Johan Banér. He almost encircled the Swedes at Torgau with superior numbers in June but Banér escaped by sacrificing parts of his baggage. In a pursuit up to Pomerania, Gallas was faster than Banér and blocked his way at Landsberg. Banér barely rescued his army by deceiving the Imperials into thinking that he would violate Polish neutrality and evacuate his army over their territory. However, he only sent his remaining baggage over the Polish border, while his troops moved westwards across the Oder. Gallas trapped him at the coastline and raised a cordon along the Peene river, taking all strongholds except the most heavily fortified, such as Stralsund or Stettin. The Swedes apparently showed readiness for peace, as their main army was locked in a few fortresses on the Baltic Sea. The new Emperor Ferdinand III was willing to compromise but the Swedish Chancellor Axel Oxenstierna eventually used his offers just to improve the French contributions in the Treaty of Hamburg in March 1638. During 1638, Gallas'