The Battle of Poltava was the decisive victory of Peter the Great (Peter I of Russia) over the Swedish Empire forces under Swedish king Charles XII, in one of the battles of the Great Northern War. It marked the turning point of the war, the end of Cossack independence, the beginning of the Swedish Empire's decline as a European great power, while the Tsardom of Russia took its place as the leading nation of north-eastern Europe The battle also bears major importance in Ukrainian national history, as Hetman of Zaporizhian Host Ivan Mazepa sided with the Swedes, seeking to create an uprising in Ukraine against the tsardom.