The invasion of Russia by Charles XII of Sweden was a campaign undertaken during the Great Northern War between Sweden and the allied states of Russia, Poland, and Denmark. The invasion began with Charles's crossing of the Vistula on 1 January 1708, and effectively ended with the Swedish defeat in the Battle of Poltava on 8 July 1709, though Charles continued to pose a military threat to Russia for several years while under the protection of the Ottoman Turks.