The Battle of Berestechko was fought between rebellious Zaporozhian Cossack, Ukrainian peasant forces, and their Crimean Tatar allies led by Hetman Bohdan Kmhelnytsky, and a Polish-Lithuanian Commonwealth army under King John II casimir. It took place in Volhynia and lasted from June 28 to June 30, 1651. The number of Polish troops is uncertain. One of the Polish commanders wrote that the Polish army had 80,000 soldiers. Modern historians estimate their numbers to be 60,000 to 63,000 soldiers. It was the biggest battle in the 17th century.
The Cossacks had around 100,000 plus 40,000 Crimean Tatar cavalry and a few thousand Turks and Vlachs. Fighting was close with the core of Cossack infantry making up for the weakness of their cavalry. Much of the decisive fighting was by the infantry and dismounted dragoons of each side. On the first day of the battle, 2000 Polish cavalry supported by six pancerni cavalry companies and winged hussars repulsed the Tatars, who suffered heavy losses. On the second day, the Poles, encouraged by their victory, deployed all available cavalry but with no support from the infantry or artillery. The Tatar cavalry won. On the third and final day, 18 Polish cavalry companies attacked the Cossack-Tatar Army with the help of the artillery and were victorious.
