Due to the legal and social oppression of the nobility Cossacks repeatedly revolted. The largest rebellions were raised under the guidance of: Kosynskiy (1591-1593), Nalyvaiko (1594-1596), Zhmaylo (1625), Fedorovych (1630), Sulima (1635), Pavlyuk (1637) and Ostryanin (1638). Cossacks again and again defended the rights of the Ukrainian population in the Commonwealth who experienced religious and national oppression regularly.