The Russo-Swedish War of 1788–1790 was fought between Sweden and Russia from June 1788 to August 1790. The war was ended by the Treaty of Värälä on 14 August 1790 and took place concomitantly with both the Austro-Turkish War (1788–1791), Russo-Turkish War (1787–1792) and Theatre War. The war was, overall, mostly insignificant for the parties involved.
King Gustav III of Sweden initiated the war for domestic political reasons, hoping to gain support from the opposition. Despite forming an alliance with the Ottoman Empire, Sweden failed to secure support from Great Britain, the Dutch Republic, and Prussia. Sweden's initial plan to attack Saint Petersburg and instigate a coup to depose Empress Catherine II did not materialize. The war led to Denmark–Norway declaring war on Sweden, but peace was eventually signed on 9 July 1789 after diplomatic intervention by Great Britain and Prussia.
During the Russo-Swedish War of 1788–1790, Sweden attempted to prevent Russian ships from cutting off coastal sea routes by building fortifications at Hangö and on its surrounding islands. Both Swedish and Russian navies engaged in multiple indecisive battles throughout the conflict, such as the Battle of Öland and the First and Second Battle of Svensksund. The last-mentioned naval battle was the biggest success of the Swedes in this war, whereas the highest Russian success at sea was the Battle of Reval. The war on land was marked by numerous skirmishes and shifting front lines but ultimately remained a stalemate. King Gustav III of Sweden, realizing the difficulty of defeating Russia and facing mounting war expenses, sought peace. Empress Catherine II of Russia, distracted by other conflicts and concerns, also desired peace. Overall, the war did not provide any lasting solutions to their respective domestic issues.
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