Wikipedia
Koliyivshchyna 1768-1769 (, from Ukr. "impaling") was a major haidamaka rebellion that broke out in Right-bank Ukraine in May 1768, caused by the social and national-religious oppression of Ukrainians by the Polish administration and nobility. The uprising resulted in a mass murder of noblemen (szlachta) and other Polish population, Jews, Uniates, and Catholic priests across the part of the country west of the Dnieper river. It was simultaneous to the Confederation of Bar and a de facto civil war in Poland. The rebellion was fueled by the circulation of a fictitious proclamation of support and call to arms by Russia's Empress Catherine II. Eventually the uprising was crushed by Russian troops, aided by Polish army. Its leaders, Ivan Gonta, was tortured to death while Maksym Zalizniak was exiled to Siberia.
The peasant rebellion quickly gained momentum and spread over the territory from the right bank of the Dnieper River to the river Syan. At Uman it led to a massacre of legendary proportions. Poles, Jews and Uniates were herded into their churches and synagogues and killed in cold blood. In three weeks of unbridled violence the rebels slaughtered 20,000 people, according to numerous Polish sources. The leaders of the uprising were Cossacks Maksym Zalizniak and Ivan Gonta. The latter was a Registered Cossack who changed sides and joined Zalizniak at Uman while being sent by Polish Count Franciszek Salezy Potocki to protect it. Gonta was in fact а sotnyk (i.e. a commander of a unit of 100 sabers) of the Uman Regiment.
The rebellion was suppressed by the joint forces of Polish and Russian armies, with numerous hangings, decapitations, quarterings and impalings.