In 1843, the Interior Ministry of the Czarist government convened a rabbinical conference in the Russian capital of Petersburg, to the end of imposing changes in Jewish communal life and religious practice. Rabbi Menachem Mendel of Lubavitch (1789-1866, known as the "Tzemach Tzeddek" after his Halachic works by that name) was invited; as a primary figure in the leadership of Russian Jewry, his compliance was required to lend legitimacy to the government's proposed "reforms". In the course of the conference, the Tzemach Tzeddek was placed under arrest no less than 22 (!) times for his refusal to cooperate. When he finally departed Petersburg on the 26th of Av, he had successfully prevented the government's disruption of traditional Jewish life.

Links:
A Brief Biography of the Tzemach Tzeddek
More on the Tzemach Tzeddek