alliance known as the League of Nymphenburg to support each other's efforts to seize Habsburg territory and Bavaria's bid for the imperial election. The allies invaded on multiple fronts in mid-1741, soon occupying Austrian Tyrol, Upper Austria and Bohemia, and even threatening Vienna. Faced with a potential war of partition, Austria negotiated a secret armistice with Prussia in October and redeployed its forces to face its other enemies. Prussian forces resumed offensive operations in December, invading Moravia and blocking an Austrian drive toward Prague in early 1742. Elector Charles Albert of Bavaria won the 1742 Imperial election and became Holy Roman Emperor. In July 1742 Prussia and Austria made a separate peace in the Treaty of Berlin, under which Austria ceded the majority of Silesia to Prussia in return for Prussia's neutrality in the continuing war. In late 1742, while Prussia enjoyed the restored peace and worked to assimilate Silesia into its administration and economy, Austria fought on against Bavaria and France, reversing its losses from 1741. By the middle of 1743 Austria had recovered control of Bohemia, driven the French back across the Rhine into Alsace, and occupied Bavaria, exiling Emperor Charles Albert to Frankfurt. Prussia's withdrawal from the War of the Austrian Succession under a separate peace embittered its erstwhile allies, and the diplomatic position shifted in Austria's favour. Preparations for a second war In September 1743 Austria, Britain–Hanover, and Savoy–Sardinia concluded a new alliance under the Treaty of Worms; Britain had previously recognised Prussia's acquisition of Silesia as the mediator of the Treaty of Berlin, but this new alliance made no mention of that guarantee. Meanwhile, the Russo-Swedish War that had paralleled the First Silesian War ended in August 1743, freeing Russia to potentially take Austria's side in the ongoing succession war. The following year, Empress Elizabeth of Russia appointed as her chancellor Alexey Bestuzhev, a proponent of a pro-British and anti-French policy that entailed friendship to Austria and enmity to Prussia. Prussia sought warmer relations with Russia and briefly won a minor defensive agreement, but Russia posed a growing threat to Prussia's eastern frontier. Frederick was apprehensive that an irresistible anti-Prussian coalition might soon develop between Britain–Hanover, Saxony, Russia and Austria. He viewed the Peace of Breslau as little more than another armistice with Austria, and he needed to prevent Maria Theresa from taking revenge at her convenience when the war elsewhere was concluded. Frederick decided