Rabbi Tzvi Hirsch ben Yaakov Ashkenazi (1656, Moravia- May 2, 1718, Lemberg), known as the "Chacham Tzvi" (after a responsa by the same title), for some time rabbi of Amsterdam, was a resolute opponent of the followers of the false messiah, Sabbatai Zevi. He had a chequered career, owing to his independence of character. He visited many lands, including England, where he wielded much influence. His "responsa" are held in high esteem. Wikipedia
The definitive Wikipedia entry for Tzvi Ashkenazi. Wikipedia is the biggest multilingual free-content encyclopedia on the Internet. en.wikipedia.org/wiki/Tzvi_Ashkenazi
