This led to an overambitious campaign against Russia in 1707, however, ending in a decisive Russian victory at the Battle of Poltava (1709). The campaign had a successful opening for Sweden, which came to occupy half of Poland and making Charles able to claim the Polish throne. But after a long march exposed by cossack raids, the Russian Tsar Peter the Great's scorched-earth techniques and the cold Russian climate, the Swedes stood weakened with a shattered confidence, and enormously outnumbered against the Russian army at Poltava.