A study on a rich source base analyzed the relationship between the Cossacks S. Nalyvaiko and the Autrian emperor Rudolf II of Habsburg, who sought to attract the Cossacks to a coalition of anti-Turkish forces in Europe; the significance of the banner as a Cossack symbol is revealed, which in the traditions of the Zaporizhzhya Army had a political connotation depending on the goal and the ruler to whom the Cossacks were hired; the events of the Cossack campaigns of 1593-1595. in Moldova, Hungary and Belarus; the initiatives of the Kyiv Catholic bishop Joseph Vereshchinsky regarding the foundation of the Cossack principality in the Dnieper were highlighted and the reasons for the deterioration of relations between the Cossack army and the Polish royal power were determined. As an appendix to the work, documents of the Danzig State Archive on the activities of the Cossacks in 1592-1596 were published. (From the article: Shapoval A. Mikhail Antonovich and the Ukrainian Historical and Philological Society in Prague).