bank of the Desna River, starting from the town of Divytsia and ending with the delta of the Izota River. Its lands also stretched along both banks of the Sejm River, from the delta to the confluence of the Kleven River, and one of the tributaries of the Desna, the Oster River, from the town of Mryn to the source of this river. The first known colonel of the Nizhyn Regiment of the Khmelnytsky period was Prokopiy Shumeiko. In the summer of 1648, under his leadership, the Nizhyn Cossacks marched on the Polish fortress of Kodak. Approaching Kodak, the Cossacks laid siege to it. The Cossacks could not capture the fortress with its strong defensive lines and the presence of a Polish garrison under the command of foreign officers. Only at the end of September 1648, due to lack of food and disease, which ruthlessly mowed the besieged, the Poles went to negotiations and capitulated. The following year, 1649, part of the Cossacks of the Nizhyn Regiment opposed the Lithuanian army of Janusz Radziwill on the northern border of the Hetmanate. The successful actions of the Cossacks in this region did not allow the Lithuanians to provide significant assistance to the army of John II Casimir and contributed to the victory of B. Khmelnytsky in the military campaign of 1649. In August 1649, due to the betrayal of the Tatars, B. Khmelnytsky was forced to conclude the Peace of Zboriv with the Polish-Lithuanian Commonwealth. This register also included the Nizhyn Regiment led by Nizhyn Colonel Prokopiy Shumeyko. It is still not possible to determine the exact number of Cossacks who were registered in the Nizhyn Regiment. According to the father of Ukrainian history M. Hrushevsky, in the register of 1649 in the regiment: "Hundreds of all are recorded 11, but the last two are connected together, so in reality there are 10. Of these, 6 are Nizhyn, without any close surnames, and the seventh is probably also Nizhyn, named after his captain G. Kobyletsky. In addition, hundreds of Divotska, Berezovska, and hundreds of Nosivska and Kobyzka are connected together. Five hundred have a round of 100, the others a little less (95-99), Nosivsko-Kobyzchanska together 99… This is the smallest of the regiments: a total of 991 souls are inscribed in it." "Chronicle of Colonel Hryhoriy Hrabyanka of Hadiach" mentions 983 Cossacks, and "History of Rus" - about 1200 people. At