The Khmelnytsky Uprising, also known as the Cossack–Polish War, or the Khmelnytsky insurrection, was a Cossack rebellion that took place between 1648 and 1657 in the eastern territories of the Polish–Lithuanian Commonwealth, which led to the creation of a Cossack Hetmanate in Ukraine. Under the command of hetman Bohdan Khmelnytsky, the Zaporozhian Cossacks, allied with the Crimean Tatars and local Ukrainian peasantry, fought against Polish domination and Commonwealth's forces. The insurgency was accompanied by mass atrocities committed by Cossacks against the civilian population, especially against the Roman Catholic and Ruthenian Uniate clergy and the Jews, as well as savage reprisals by Jeremi Wiśniowiecki, the voivode of the Ruthenian Voivodeship.

The Polish–Lithuanian Commonwealth, formally known as the Kingdom of Poland and the Grand Duchy of Lithuania, or simply Poland–Lithuania, was a bi-confederal state, sometimes called a federation, of Poland and Lithuania ruled by a common monarch in real union, who was both King of Poland and Grand Duke of Lithuania. It was one of the largest and most populous countries of 16th- to 17th-century Europe. At its largest territorial extent, in the early 17th century, the Commonwealth covered almost 1,000,000 km2 (400,000 sq mi) and as of 1618 sustained a multi-ethnic population of almost 12 million. Polish and Latin were the two co-official languages, and Roman Catholicism served as the state religion.