Khmielnitski and the Tatar khan having learned that the army of the Polish king consisted of but barely 20,000 men, imagined that this was a new prey for them to devour; the more easily too as the royal army did not occupy any fortified position. Leav- ing, therefore, 45,000 Tatars and 200,000 Cossacks before the intrenchments of Zbaraz, they marched upon Zborof with 60,000 Tatars, and 100,000 Cossacks, the elite of both armies, and a strong force of artillery. They soon arrived, under cover of a thick fog, close upon the royal army, before the latter had warning of their approach. Scarcely had they sufficient time to form into battalion, when they found themselves assailed on every side. A canal, confined by a high bank, protected their rear; but this embankment having been broken through, the rear-guard, violently attacked, lost their baggage trains. The moment was critical for the fate of Poland. Neither the Tatars nor the Cossacks were able to force the centre and the right wing, where they were repulsed with immense loss; but the left wing, raked by the artillery and attacked by overwhelming numbers, after losing all its officers, was exposed to the greatest danger. Thither the king hastened, and his presence revived the spirit of the soldiers, who performed prodigies of valour.
Nightfall brought no cessation to the fury of the assailants: during the construction of a rampart with the heaped-up bodies of the slain, the Polish generals convoked a council of war, wherein a resolution was come to, confirmed by an oath, either to conquer or die. Further, it was decided, that measures should be taken to detach the khan from the Cossack alliance. When daylight dawned on this terrible night, the battle was renewed with increased determination on either side. Whilst a hand-to-hand conflict, sustained by all the rancour of mutual hate and animosity, was raging with deadly force amongst the combatants, whole ranks were swept away at once by the fearful discharges of artillery. Ultimately, however, the immense superiority in numbers was forced to yield to the steady power of military tactics, and the resistless courage of despair. The Poles were victorious on all points. Khmielnitski having received unfavourable news from Lithuania, where Prince Radziwill was everywhere defeating the Cossacks with terrific energy, and having reason, from hour to hour, to expect the arrival of that victorious general with 15,000 troops to reinforce the royal army; finding, moreover, that the khan of the Tatars had withdrawn his support from the Cossack cause, and had actually concluded an armistice with the Polish king; Khmielnitski, thus hampered and thwarted in his plans, found himself under the necessity of likewise agreeing to a suspension of hostilities, and of soliciting, in person, his pardon from the king; an event which afforded some temporary respite to unhappy Poland. The convention of Zborof (17th August, 1649,) was by no means favourable to Khmielnitski himself. He was therein treated as a rebellious subject, compelled to disband his army, and forbidden for the future to receive deserters or refugees; he was to be permitted to retain no greater number than 40,000 registered Cossacks — and these merely for the defence of the frontiers, conformably to the ancient stipulations settled by King Batory. But on the other hand, an amnesty was granted to all the Cossacks, who were to be permitted in future to elect their own attamans and to distil brandy: they were also to have the right of hunting and fishing throughout the south of the Ukraine; they were to enjoy the free exercise of their religion; and a promise was even made them to admit to the Senate and to the Diet a Cossack, with the title of Palatine of Kiow, as likewise a metropolitan of the Greek religion. Further, there was accorded to each registered Cossack, a ducat in money, together with sufficient cloth for his dress.