Prince Janusz Radziwiłł, also known as Janusz the Second or Janusz the Younger was a noble and magnate in the Polish–Lithuanian Commonwealth. Throughout his life he occupied a number of posts in the state administration, including that of Court Chamberlain of Lithuania, Field Hetman of Lithuania and Grand Hetman of Lithuania. He was also a voivode of Vilna Voivodeship, as well as a starost of Samogitia, Kamieniec, Kazimierz and Sejwy. He was a protector of the Protestant religion in Lithuania and sponsor of many Protestant schools and churches.

The Russo-Polish War of 1654–1667, also called the Thirteen Years' War, Muscovite War of 1654-1667 and the First Northern War, was a major conflict between the Tsardom of Russia and the Polish–Lithuanian Commonwealth. Between 1655 and 1660, the Swedish invasion was also fought in the Polish–Lithuanian Commonwealth and so the period became known in Poland as "The Deluge" or Swedish Deluge.