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According to a chronicle of 1864 written by Samuil Velichko, Ostranin, who had just been elected Hetman, issued an address to the Little Russian people on the eve of the campaign in March 1638. He declared that he would "go with his army to the Ukraine in order to liberate the Orthodox people from the yoke of oppression and torment of the Polish tyranny and claim vengeance for grievances, ruin and torturous abuse... suffered by the entire Russian populace, living on both sides of the Dnieper."
Ostranin also called on the people of Ukraine to join the insurgency and to beware of the Registered Cossacks. His leaflets were spread across Ukraine, reaching as far as Pokuttia. His appeal was carried and distributed by the Cossack elders, bandurists, youth, and according to Ostranin, even Orthodox monks. People began to prepare for an uprising, some going to Zaporozhye, while others sent food, money, and gunpowder.
The rebels left Zaporozhye and divided themselves into three detachments. The first, moving down the left bank of the Dnieper, was led by Ostranin himself. His force took Kremenchug and moved onto Khorol and Omel'nyk. The second body of troops, consisting of a flotilla led by Guney, took the river crossings in Kremenchug, Maksimovka, Buzhin and Chigirin. The third force occupied the right bank of the Dnieper.
Read more about this topic: Ostrzanin Uprising