Britain now threatened to withdraw its subsidies if Frederick did not consider offering concessions to secure peace. As the Prussian armies had dwindled to just 60,000 men and with Berlin itself about to come under siege, the survival of both Prussia and its king was severely threatened. Then on 5 January 1762 the Russian Empress Elizabeth died. Her Prussophile successor, Peter III, at once ended the Russian occupation of East Prussia and Pomerania (see: the Treaty of Saint Petersburg (1762)) and mediated Frederick's truce with Sweden. He also placed a corps of his own troops under Frederick's command. Frederick was then able to muster a larger army, of 120,000 men, and concentrate it against Austria. He drove them from much of Silesia after recapturing Schweidnitz, while his brother Henry won a victory in Saxony in the Battle of Freiberg (29 October 1762). At the same time, his Brunswick allies captured the key town of Göttingen and compounded this by taking Cassel.