The Seven Years War was provoked by the attempt of Prussian King Friedrich II to expand his state territories. During 1756 and 1757 Prussian forces conducted a successful offensive and defeated their enemies - Austrians and Frenchmen. In 1756 Friedrich II occupied Saxony and a part of Northern Bohemia. He was victorious near Prague, and then in the battle of Leiten in 1757 Prussian troops smashed the numerically superior army of Austria. However, Russian forces and their allies Austria and France entered Eastern Prussia, foiled all Friedrich's plans, and recaptures all territories Friedrich seized during the campaign of 1756-57. Russian army inflicted a rigorous defeat on Prussia in the battles of Zorndorf (now Sarbinowo, Poland) and Kunersdorf. Only the death of Russian Tzarina Elisabeth saved Prussia from discomfiture, since Russians not only broke off the alliance with Austria but also decided to support Prussia. As a result, Prussia remained inside its prewar borders, but did not give up hope of conquering the neighboring territories.