Upvote:3
Wikipedia says that Jews were acceptable to the Zaporozhian Cossacks until they became an economic threat in 17th century.
The idea was briefly resurrected by Potemkin a century later.
Upvote:3
This is a difficult question to answer, because of the many meanings of a Cossack, as shown below:
Isaac Babel, for instance, the author of Red Cavalry (early 20th century), was known as the Jewish Cossack. See Jon Leonard, The Jewish Cossack, the Nation, Nov., 26, 2001, p. 14 However, a relatively scientific book about Ukraine (which included the Cossacks) written in the 19th century by Henry d. Krasinski, Cossacks of the Ukraine, does not mention any Jewish Cossacks (probably because Cossacks is used in its ethnic meaning), and intermarriage did not really exist (wild guess, if it happened it was very short-lived).
Thus, this means that the question is whether there were any Jewish lawless criminals enrolled the tzarist army. And that is a very difficult question to answer, other than Issac Babel.