Shneur Zalman of Liadi
Rabbi Shneur Zalman of Liadi, the founder of the movement, was twice arrested by Tsar Paul I on trumped up charges but released both times. In the face of Napoleonic invasion, Schneur Zalman sided with the Tsar, believing that emancipation and freedom would lead to spiritual malaise.
During his life, the controversies between the Hasidim and Mitnagdim intensified in many ways. Some issues involved in the disagreements were the best type of knife to be used for ritual slaughter as well as the appropriate conduct during, and phrasing of prayers. As a result, the Hasidim were subjected to bans, though these lessened during the lives of Schneur Zalman's son, Rabbi Dovber Schneuri and grandson, Rabbi Menachem Mendel Schneersohn. Although Shneur Zalman and a fellow Hasidic leader, Menachem Mendel of Vitebsk (or, according to the tradition in the Soloveitchik family, Levi Yitzchok of Berditchev), once attempted to see the Vilna Gaon to persuade him of the legitimacy of Hasidism, the Gaon refused to meet with them.
Read more about this topic: Chabad-Lubavitch Related Controversies