page_title: Second Northern War
section_title: Brandenburgian-Swedish alliance and Russia's war on Sweden
hierarchical_section_title: Second Northern War / Brandenburgian-Swedish alliance and Russia's war on Sweden
context_page_description: The Second Northern War was fought between Sweden and its adversaries the Polish–Lithuanian Commonwealth, the Moscow Tsardom, Brandenburg-Prussia, the Habsburg Monarchy and Denmark–Norway. The Dutch Republic often intervened against Sweden in an informal trade war but was not a recognized part of the Polish–Danish alliance.
  In 1655, Charles X Gustav of Sweden invaded and occupied western Poland–Lithuania, the eastern half of which was already occupied by Russia. The rapid Swedish advance became known in Poland as the Swedish Deluge. The Grand Duchy of Lithuania became a Swedish fief, the Polish–Lithuanian regular armies surrendered and the Polish king John II Casimir Vasa fled to the Habsburgs. Frederick William, Elector of Brandenburg and Duke of Prussia initially supported the estates in Royal Prussia, but allied with Sweden in return for receiving the Duchy of Prussia as a Swedish fief. Exploiting the hurt religious feelings of the Roman Catholic population under Protestant occupation and organizing Polish–Lithuanian military leaders in the Tyszowce Confederation, John II Casimir Vasa managed to regain ground in 1656.
context_section_description: On 25 June 1656, Charles X Gustav signed an alliance with Brandenburg: the Treaty of Marienburg granted Greater Poland to Frederick William in return for military aid. While the Brandenburgian elector was free of Swedish vassalage in Greater Poland, he remained a Swedish vassal for the Duchy of Prussia. Brandenburgian garrisons then replaced the Swedish ones in Greater Poland, who went to reinforce Charles X Gustav's army. On 29 June however, Warsaw was stormed by John II Casimir, who had drawn up to Charles X Gustav with a force of 28,500 regulars and a noble levy of 18,000 to 20,000. Thereupon, Brandenburg actively participated in the war on the Swedish side, prompting John II Casimir Vasa to state that while his Tartars already had the Swedes for breakfast, he would now take Frederick William into custody, where neither sun nor moon would shine.
  Already in May 1656, Alexis of Russia had declared war on Sweden, taking advantage of Charles being tied up in Poland, and Livonia, Estonia and Ingria secured only by a Livonian army of 2,200 infantry and 400 dragoons, Magnus de la Gardie's 7,000 men in Prussia, and 6,933 men dispersed in garrisons along the Eastern Baltic coast. Alexis invaded Livonia in July with 35,000 men and took Dünaburg.
  In late July, Danzig was re-inforced by a Dutch garrison, and a combined Danish and Dutch fleet broke the naval blockage imposed on Danzig by Charles X Gustav. On 28–30 July, a combined Brandenburgian-Swedish army was able to defeat the Polish–Lithuanian army in the Battle of Warsaw, forcing John II Casimir to retreat to Lublin. In August, Alexis' army took Livonian Kokenhausen (Koknese), laid siege to Riga and Dorpat (Tartu) and raided Estonia, Ingria and Kexholm.
  On 4 October, John II Casimir stormed Łęczyca in Greater Poland before heading for Royal Prussia, and on 8 October, Wincenty Korwin Gosiewski with 12,000 to 13,000 Lithuanian and Crimean Tartar cavalry overran a Brandenburgian-Swedish force in the Battle of Prostken in Ducal Prussia. Gosiewski then ravaged Ducal Prussia, burning 13 towns and 250 villages, in a campaign that entered folklore because of the high death toll and the high number of captives deported to the Crimea.
  On 22 October, Gosiewski was defeated by Swedish forces in the Battle of Filipów and turned to Lithuania. Also on 22 October, besieged Dorpat surrendered to Alexis, while the Russian siege of Swedish-held Riga was lifted. John II Casimir meanwhile took Bromberg (Bydgoszcz) and Konitz in Royal Prussia, and from 15 November 1656 until February 1657 stayed in Danzig, where a Swedish siege had to be lifted due to Dutch intervention, just 55 kilometers away from Charles X Gustav's quarters in Elbing.
caption: Swedish King Charles X Gustav in skirmish with Polish Tatars during the Battle of Warsaw
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