The Seven Years' War was provoked by the attempts of Prussian King Frederick II to expand his state territories. During 1756 and 1757, Prussian forces conducted a successful offensive and defeated their enemies, Austria and France. In 1756, Frederick II occupied Saxony and part of Northern Bohemia. He was victorious near Prague, and in the Battle of Leuthen in 1757 Prussian troops smashed the numerically superior Austrian army. However, Russian forces and their allies Austria and France entered eastern Prussia, foiled all Frederick's plans, and recaptured all territories that he had seized during the campaign of 1756-57. The Russian army inflicted a rigorous defeat on Prussia in the Battles of Zorndorf (now Sarbinowo, Poland) and Kunersdorf. Only the death of Russian Tsarina Elisabeth saved Prussia from discomfiture, since Russia not only broke off its alliance with Austria but also decided to support Prussia. As a result, Prussia remained inside its prewar borders, but did not give up the hope of conquering their neighbouring territories.