Battle of Vilnius (1655)
The Battle of Vilnius, Wilno, or Vilna was an attack by Russian and Cossack forces on Vilnius, the capital of the Grand Duchy of Lithuania within the Polish–Lithuanian Commonwealth, that occurred on 8 August 1655 during the Russo-Polish War (1654–67). The Polish–Lithuanian forces under the leadership of Great Hetman Janusz Radziwiłł were defeated by the Russian army of Alexis of Russia. It was the first time that a foreign power managed to capture the Vilnius Castle Complex. The six-year Muscovite occupation that followed resulted in a major depopulation and a decline of the city for many years to come. The defeat was one of the reasons Janusz Radziwiłł and several other Lithuanian magnates surrendered the Grand Duchy to Sweden at the Union of Kėdainiai.