The Poles were by now well aware of what was going on. They sent an army under the Crown Hetman Potocki and the Field Hetman Kalinowski to Fort Kodak to keep the Zaporozhians from moving northward. This time they were too late. The King, who had himself incited the Kozak leaders, urged his officers not to fight. They decided to do so and sent the son of Potocki with a force of 1500 Poles and 2500 registered Kozaks overland to Fort Kodak, as a preliminary reinforcement for the troops stationed there. Bohdan learned of this movement and with some 8,000 Kozaks, by forced marches, he surrounded the young and unsuspecting Potocki at Zhorty Vody (the Yellow Waters) on April 29, 1648. Seeing himself outnumbered, Potocki fortified a camp, where he was besieged and waited for the aid of the Kozaks who were coming down the Dnyeper on barges. Bohdan reached these Kozaks, easily won them to his cause, and added them to his own forces. When the news of this reached the Poles, Potocki realized that his only chance was to cut his way out and reach his father and the main body of the troops at Korsun. He failed disastrously in this and was compelled to ask for terms. Khmelnitsky allowed them to retire without their artillery. They had barely started on their march when the forces of the Tatars under Tugai Khan attacked the disordered and heavily laden Polish force and destroyed them almost to a man. Stephen Potocki was taken prisoner but died of his wounds the next day. The news of this terrible defeat struck terror into the hearts of Potocki and Kalinowski. They realized that the entire country would soon be up in arms and that their plan of cutting off the Zaporozhe from the north had completely failed. Yet they disagreed on everything else. Kalinowski wanted to press on to Fort Kodak, Potocki wanted to stay where they were, and the lesser officers called for a retreat. This was finally decided upon and as they moved north, Potocki commenced to set fire to the villages and burned the city of Korsun for terroristic purposes. The result was not what he had expected. He merely aroused the anger of the population, who joined the Kozaks. In the meanwhile the Tatars attacked the army in front and Khmelnitsky sent to the rear a detachment of the Korsun regiment of Kozaks under the command of a Scotch adventurer, known by the name of Maksym Krivonos (Crooked-nose). Everything went like clockwork for the Kozaks. The Poles fell into the ambuscade and lost all semblance of discipline. One detachment under Prince Koretsky succeeded with heavy loss in cutting its way to safety, but the two hetmans, Potocki and Kalinowski, and over one thousand men were captured. The rest were killed. The prisoners were turned over to the Tatars and the leaders were sent to the Crimea until they should pay 20,000 gold coins each.