 Complete the following phrase:  A Polish Brethren, Niemirycz defended his fellow Arians in court and in parliament in the 1640s, and supported a fellow Protestant George II Rákóczi as candidate for the Polish-Lithuanian throne in 1648, when king Władysław IV Vasa died in the mist of war. Because of the Cossack Uprising of 1648 he had to evacuate his family to Warsaw, and took limited part in fighting against the rebellious Cossacks and serfs, advocating moderation along the lines of Kiev voivode Adam Kisiel. He returned to his estates in 1649 but the massacre of Polish army by the Cossacks and Crimean Tatars at Batoh 