Khmelnytsky Uprising

The 1648 Ukrainian Cossack (Kozak) rebellion or Khmelnytsky Uprising, which started an era known as the Ruin (in Polish history as The Deluge), undermined the foundations and stability of the Commonwealth. The nascent Cossack state, the Cossack Hetmanate, usually viewed as precursor of Ukraine, found itself in a three-sided military and diplomatic rivalry with the Ottoman Turks, who controlled the Tatars to the south, the Commonwealth of Poland and Lithuania, and the Tsardom of Muscovy to the East.