The Great Northern War (1700–21) was a conflict in which a coalition led by the Tsardom of Russia successfully contested the supremacy of the Swedish Empire in northern Central Europe and Eastern Europe. The initial leaders of the anti-Swedish alliance were Peter I the Great of Russia, Frederick IV of Denmark–Norway and August II the Strong of Saxe-Poland-Lithuania. Frederik IV and August II were forced out of the alliance in 1700 and 1706 respectively, but re-joined it in 1709. George I of Brunswick-Lüneburg (Hanover) joined the coalition in 1714 for Hanover and in 1717 for Britain, and Frederick William I of Brandenburg-Prussia joined it in 1715.

Charles XII led the Swedish army. On the Swedish side were Holstein-Gottorp, several Polish and Lithuanian magnates under Stanisław Leszczyński (1704–10) and cossacks under the Ukrainian Hetman Ivan Mazepa (1708–10). The Ottoman Empire temporarily hosted Charles XII of Sweden and intervened against Peter I.

Northern War may refer to:

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Great Northern may refer to:

Peter the Great, Peter I or Pyotr Alexeyevich Romanov (Russian: Пётр Алексе́евич Рома́нов, Пётр I, Pyotr I, or Пётр Вели́кий, Pyotr Velikiy) (9 June [O.S. 30 May] 1672 – 8 February [O.S. 28 January] 1725) ruled the Tsardom of Russia and later the Russian Empire from 7 May [O.S. 27 April] 1682 until his death, jointly ruling before 1696 with his half-brother. In numerous successful wars he expanded the Tsardom into a huge empire that became a major European power. According to historian James Cracraft, he led a cultural revolution that replaced the traditionalist and medieval social and political system with a modern, scientific, Europe-oriented, and rationalist system.