only minor skirmishes, after which Lithuanian troops retreated to their previous positions. The next significant military action with the participation of the Cossacks of the Nizhyn Regiment began in May 1654, when Russia, in accordance with the terms of the Pereyaslav Council, declared war on the Commonwealth and invaded the territory of Belarus. To help the Russians, the hetman sent the Chernihiv, Nizhyn and Pereyaslav regiments led by Colonel I. Zolotarenko of Nizhyn, who received the post of acting hetman. The total number of Cossack troops was 20 thousand people. In addition, Hetman B. Khmelnytsky, according to Hryhoriy Hrabyanka, allowed anyone who wanted to go on a campaign. Modern Nizhyn local historian Oleksandr Urivalkin provides information about the constituent parts of I. Zolotarenko's army: Nizhyn Regiment of G. Kobyletsky, Regiment of Tymofiy Zolotarenko, Chernihiv Regiment of Pobodaila, Starodub Regiment of Pasha, Borznyansky Regiment of Zabila and S. Kurbatsky, Regiment of Yu. Semenov… and V. Zolotarenko's detachment, which acted directly together with Oleksiy Mykhailovych's troops in the Smolensk region. Nizhyn Regiment and Hetman I. Mazepa In 1687 a coup d'etat was carried out, during which the officer of the Nizhyn Regiment also took part. Ivan Mazepa was appointed head of the Hetmanate, which in turn only deepened the internal conflicts between the Cossacks. Immediately after his election in 1687, Hetman I. Mazepa signed with the Russian government the Kolomatsky Articles, which determined the place and status of the Left Bank of Ukraine as part of the Moscow State. Thus, the second article of the agreement, submitted in the Chronicle of Samiil Wieliczka, directly concerns the city of Nizhyn and is entitled "On the voivode and hostages in Kiev, Pereyaslav, Chernihiv, Nizhyn, Ostra…" It was in these cities were to be Russian voivodes, who relied on pre-defined in the Ukrainian-Russian treaties functions and powers. The initial period of the new hetman's rule was marked by an almost radical change of persons who held regimental and hundreds of positions in the Cossack regiments of the Left Bank of Ukraine. According to S. Pavlenko's calculations, during 1687-1693 the personnel potential of the Hetmanate was renewed by almost 70% [10, p.26]. These changes also affected the Nizhyn Regiment led by Stepan Zabila. The following representatives of the Cossack officers were sent to the hundreds of towns of the regiment: Hryhoriy Samoilovych to Nova Mlyny, Samiylo Afanasiev to Verkiivka, Karpo Mankivsky to Sheptaki and others. In