Nevertheless, the conquest of Prague failed and moreover, the king had to deal with Russian forces attacking East Prussia while Austrian troops entered Silesia. His situation worsened, when Austrian and Russian forces united to inflict a crushing defeat on him at the 1759 Battle of Kunersdorf. Frederick, on the brink, was saved by the discord among the victors in the "Miracle of the House of Brandenburg", when Empress Elizabeth of Russia died on 5 January 1762 and her successor Peter III concluded peace with Prussia. By the 1763 Treaty of Hubertusburg, Austria, for the third time, had to acknowledge the Prussian annexations. The usurper kingdom had prevailed against the European great powers and would play a vital future role in the "Concert of Europe".