situation strongly deteriorated; while Banér received fresh reinforcements from Sweden, Gallas gained only insignificant support from his allies Brandenburg-Prussia and Saxony. In October 1638, Banér broke through Gallas' cordon and reconquered Mecklenburg. The Imperials were unable to sustain their army in the devastated area any longer and first retreated across the Elbe, then to Silesia, plundering and partially dissolving in the progress. After Gallas' retreat, Banér pushed into Saxony, defeating the Saxon army at Chemnitz in April 1639. The Swedes advanced even further entering Bohemia in May as the first enemy since 1634. At first left in command, Gallas focused on defending Prague against Swedish siege attempts. Unable to expel the Swedes from Bohemia and confronted with declining army morale and discipline, Gallas was replaced by Archduke Leopold Wilhelm in September. The emperor wanted Gallas to stay as counselor in Vienna, but he chose to return to Trento and to administer his various possessions for the next few years. Return as commander In March 1643, Gallas returned to succeed the Archduke and the interim commander Piccolomini who both resigned following their defeat at Breitenfeld. Gallas anticipated the march of the Swedes under Lennart Torstensson from Saxony to Moravia and tried to block his way with a defensive position at Hradec Králové as well as denying the Swedes any crossing of the Elbe. However, Torstensson feinted an attack at Brandeis while gaining a crossing at Mělník. This allowed Torstensson to reach Moravia and resupply the occupied Olomouc. Gallas followed him over Brno and again took a strong defensive position in front of Torstensson. Instead of seeking battle, Gallas harassed him in skirmishes with the superior Imperial light cavalry and sent a diversion under Krockow to Pomerania. At the end of the year, the Swedes surprisingly left to attack Denmark in what became the Torstenson War. In the next year, Gallas was ordered to march to Holstein to Denmark's aid. Being himself very skeptical about the prospects of this campaign, he delayed his departure until May and slowly moved up to Kiel that he recaptured from Sweden in August. The Swedish fleet had been trapped in the Bay of Kiel after the Battle of Colberger Heide but Gallas arrived a few days too late to bombard it from land. Torstensson was already in control of Jutland and bypassed Gallas' army after a short confrontation at the Eider to threaten their supply lines.