Khmelnytsky Uprising (Hebrew: גזרות ת"ח-ת"ט) was the uprising in the Ukrainian territories against the Polish-Lithuanian that began in early 1648 under the leadership of Bohdan Khmelnytsky, a Cossack officer.
The Uprising started as the rebellion of the Cossacks, but as other Orthodox Christian classes of the Ukrainian palatinates joined them, the ultimate aim became a creation of Ukrainian autonomous state.
The entire Jewish population of the Commonwealth in that period (1618 - 1717) has been estimated to be about 200,000. Most of them lived outside Ukraine in the territories unaffected by the uprising. The Jewish population of Ukraine of that period is estimated at about 50,000. But, all the sources from that time agree that Jewish Ukrainian communities were devastated by the uprising and ensuing massacres. During that period total Jewish casualties are estimated of at least 100,000.
Although many modern sources still give estimates of Jews killed in the uprising at 100,000 or more, others put the numbers killed on between 40,000 and 100,000, and recent academic studies have argued fatalities were even lower.
A 2003 study by Israeli demographer Shaul Stampfer of Hebrew University dedicated solely to the issue of Jewish casualties in the uprising concludes that 18,000 - 20,000 Jews were killed out of a total population of 40,000.
For me the number is less important than the event itself, which is a critical point in Israel's history.