In early September 1741, the French entered the war against Austria, and together with their ally, the Electorate of Bavaria, marched on Prague. Meanwhile, Frederick, as well as other members of the League of Nymphenburg, sponsored the candidacy of his ally Charles of Bavaria to be elected Holy Roman Emperor. Charles was crowned on 2 February 1742 and claimed the crown of Bohemia as his own. With Prague under threat, the Austrians pulled their army out of Silesia to defend Bohemia. When Frederick pursued them into Bohemia and blocked their path to Prague, the Austrians counter-attacked on 17 May 1742, initiating the Battle of Chotusitz. In this battle, Frederick's retrained cavalry proved more effective than at Mollwitz, but once more it was the discipline of the Prussian infantry that won the field. The battle exhausted both sides, but the Austrians fled the field allowing Frederick to claim a major victory. This victory, along with the Franco-Bavarian forces capturing Prague, forced the Austrians to seek peace with Frederick. The terms of the Treaty of Breslau between Austria and Prussia, negotiated in June 1742, gave Prussia all of Silesia and Glatz County, with the Austrians retaining only the portion called Austrian or Czech Silesia. Prussian possession of Silesia added one of the most densely industrialized German regions to Frederick's kingdom and gave it control over the navigable Oder River. The conquest nearly doubled the kingdom's population and increased its territory by a third. In 1744, Frederick also successfully claimed his inheritance to the minor territory of East Frisia on the North Sea coast of Germany when he occupied the territory after its last ruler died without issue.