Great Northern War

In the Great Northern War (1700–1721) a coalition led by Russia successfully contested the supremacy of Sweden in Northern, Central and Eastern Europe. The initial leaders of the anti-Swedish alliance were Peter I of Russia, Frederick IV of Denmark–Norway and Augustus II the Strong of Saxony-Poland-Lithuania. Frederick IV and Augustus II were defeated by Sweden, under Charles XII, and forced out of the alliance in 1700 and 1706, respectively, but rejoined it in 1709 after the defeat of Charles XII at the Battle of Poltava. George I of Great Britain and the Electorate of 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. Swedish allies included Holstein-Gottorp, several Polish magnates under Stanisław I Leszczyński (1704–1710) and Cossacks under the Ukrainian HetmanIvan Mazepa (1708–1710). The Ottoman Empire temporarily hosted Charles XII of Sweden and intervened against Peter I.

The war began when Denmark–Norway, Saxony and Russia, sensing an opportunity as Sweden was ruled by the young Charles XII, formed a coalition against Sweden. Denmark invaded Sweden's ally Holstein-Gottorp, while Saxony and Russia declared war on the Swedish Empire and attacked Swedish Livonia and Swedish Ingria, respectively. Sweden parried the Danes at Travendal (August 1700) and the Russians at Narva (November 1700), and in a counter-offensive pushed Augustus II's forces through the Polish–Lithuanian Commonwealth to Saxony, dethroning Augustus on the way (September 1706) and forcing him to acknowledge defeat in the Treaty of Altranstädt (October 1706). The treaty also secured the extradition and execution of Johann Reinhold Patkul, architect of the alliance seven years earlier. Meanwhile, the forces of Peter I had recovered from defeat at Narva and gained ground in Sweden's Baltic provinces, where they cemented Russian access to the Baltic Sea by founding Saint Petersburg in 1703. Charles XII moved from Saxony into Russia to confront Peter, but the campaign ended in 1709 with the destruction of the main Swedish army at the decisive Battle of Poltava (in present-day Ukraine) and Charles' exile in the Ottoman town of Bender. The Ottoman Empire defeated the Russian–Moldavian army in the Pruth River Campaign, but that peace treaty was in the end without great consequence to Russia's position.

After Poltava, the anti-Swedish coalition revived and subsequently Hanover and Prussia joined it. The remaining Swedish forces in plague-stricken areas south and east of the Baltic Sea were evicted, with the last city, Tallinn, falling in the autumn of 1710. By 1714, Russia had occupied Finland.

On 18 October 1709, Sweden received Denmark-Norway’s declaration of war, presented as a response to the alleged maltreatment of Danes by Sweden in Scania. Swedish victory at Helsingborg amounted to only a brief respite before ultimate defeat in the west.

From June 1716, Denmark and Russia prepared a joint invasion of Sweden proper, which the Tsar envisioned as dealing the Swedish king a decisive blow. Earlier that year, Charles XII had invaded south-eastern Norway, but a string of successive defeats, together with the systematic disruption of Swedish logistics by the Norwegians, had forced him back towards the border. In June and July, a renewed offensive against Fredrikshald, or Halden, was frustrated by the combined efforts of the town's garrison and inhabitants. The campaign was finally abandoned after Tordenskjold, the Norwegian naval hero, captured almost the entire Swedish supply and transport fleet at Dynekilen, forcing Charles XII to finally retreat across the border. In the meantime, a Danish-Russian invasion force was assembling across the strait. Severe delays, however, pushed the operation into autumn and, together with growing distrust and strategic divergence between the allied monarchs, ultimately led to its cancellation.

In 1718, Sweden launched a second and even larger campaign against Norway. Charles XII was ultimately killed in the trenches before Fredriksten, while a second Swedish field army was forced onto the Carolean Death March during its retreat from Trøndelag, losing most of its men. The failure of the Norwegian campaign constituted a severe strategic defeat for Sweden and effectively brought its offensive war to an end.

The war ended with the defeat of Sweden, leaving Russia as the new dominant power in the Baltic region and as a new major force in European politics. The Western powers, Great Britain and France, became caught up in the separate War of the Spanish Succession (1701–1714), which broke out over the Bourbon Philip of Anjou's succession to the Spanish throne and a possible joining of France and Spain. The formal conclusion of the Great Northern War came with the Swedish-Hanoverian and Swedish-Prussian Treaties of Stockholm (1719), the Dano-Swedish Treaty of Frederiksborg (1720), and the Russo-Swedish Treaty of Nystad (1721). By these treaties Sweden ceded its exemption from the Sound Dues and lost the Baltic provinces and the southern part of Swedish Pomerania. The peace treaties also ended its alliance with Holstein-Gottorp. Hanover gained Bremen-Verden, Brandenburg-Prussia incorporated the Oder estuary (Stettin Lagoons), Russia secured the Baltic Provinces, and Denmark strengthened its position in Schleswig-Holstein. In Sweden, the absolute monarchy had come to an end with the death of Charles XII, and Sweden's Age of Liberty began.