The date is significant within the Hasidic movement. Rabbi Shneur Zalman of Liadi (Hebrew: שניאור זלמן מליאדי), the first Rebbe of Chabad (also known as the "Alter Rebbe" in Yiddish) was informed upon by a certain Avigdor and arrested on trumped-up charges of supporting the Ottoman Empire. His informers pointed to the fact that he would urge his followers to send money to the Land of Israel as "evidence" of his alleged insurrectionist aspirations (in fact, the money was sent to support poor Jews). At the time, the Land of Israel was a part of the Ottoman Empire, which was at war with Russia. Rabbi Shneur Zalman was charged with treason, and released in the secular year 1798 on the Jewish date of Tuesday, 19 Kislev. The fifty-three days of Rabbi Shneur Zalman's imprisonment are said to correspond to the fifty-three chapters of the first section of the Tanya.
This day is regarded as a divine vindication of the Chabad movement, and has thus been celebrated ever since by Chabad Hasidim with joyous farbrengens. It is regarded as "the New Year of Chassidus (Hasidism)," when each Chassid wishes the other, "may you be signed and sealed for a good year in the study and ways of Chassidus." Tachanun is not recited. The last verses of Psalm 55, "He has redeemed my soul in peace," are traditionally sung on this day. These verses are a reference to the experienced by the Alter Rebbe on this day. Rabbi Shneur Zalman said: "Whoever participates in my celebration will merit to see nachas from his descendants." The day is also marked by many other non-Chabad Chassidic groups.
When the Alter Rebbe left prison he was mistakenly brought to the home of a Misnagid (one opposed to Chassidus), who caused him to suffer with his questions. Afterwards, the Alter Rebbe said that the three hours he spent at the Misnaged’s home were more difficult than all the time he had spent in prison. In commemoration of the fact that the Alter Rebbe's liberation was not complete until he left the Misnagid's house, Chassidim mark 20 Kislev as a day of liberation as well.
During Rabbi Shneur Zalman's imprisonment he was questioned by an erudite government minister, who posed the following question:
"The verse states that G-d called to man and said to him, 'Where are you?' Didn't G-d know where Adam was?" Rabbi Shneur Zalman answered him in accordance with Rashi's explanation that God asked Adam the question "Where are you?" in order to gently begin conversing with Adam, so that Adam would not become startled and disconcerted by God's sudden appearance. The minister indicated that he was aware of that answer, but he wanted to hear Rabbi Shneur Zalman's explanation.
After ascertaining that the minister believed in the eternality of the Torah and its directives, Rabbi Shneur Zalman replied: "When a person is, for example, so and so many years old (mentioning the exact age of his questioner), G-d asks him: Where are you? Are you aware of why you were created on this earth? Are you aware of what you are expected to do and how much you actually have done?"
Chasidic lore tells that the Maggid of Mezeritch and the Baal Shem Tov came to visit Rabbi Shneur Zalman in prison. Although they had died, they came as souls within bodies. Rabbi Yosef Yitzchok Schneersohn is reputed to have once visited the cell (when he was in Saint Petersburg in the summer of 1911), and when he returned, his father, Rabbi Sholom Dovber Schneersohn, the fifth Chabad Rebbe, asked him if the cell had enough room for three people, which implies that Rabbi Sholom Dovber believed that they had appeared as souls in bodies.
Rabbi Yaakov of Marvege (Korebil), a twelfth-century Tosafist and Kabbalist, wrote a book called "Responsa from Heaven," in which he recorded halachic responsa he had heard from Heaven. After discussing the concept that one should only study Torah after immersion in a mikveh, he describes 19 Kislev as "a day that will herald good tidings." On this Rabbi Menachem Mendel Schneerson commented:Throughout the generations, that addition puzzled scholars. What were the “good tidings” received on Yud-Tes Kislev? Scholars of the later generations concluded that the phrase must refer to the Alter Rebbe’s liberation. No other event occurred on 19 Kislev that would cause the day to be labeled a day which “will herald good tidings.”
19 Kislev 1772 is also the date of the Yom Hillula (passing) of the Maggid of Mezritch, the successor of the Baal Shem Tov (the founder of Hasidism).
19 Kislev is also considered to mark the day upon which Rabbi Shneur Zalman was conceived, for he was born exactly nine months later, on 18 Elul.
19 Kislev 1809 was also the birth date of the Alter Rebbe of Chasidei Z'ichlin, HaRebi Shmuel Abba zatzal. It was celebrated as the birthdate of the Z'ichlin Chasidut until 95% of the followers were murdered in the holocaust.
19 Kislev is also the day in 2003 that Saddam Hussein was captured.
19 Kislev is also the day in 2011 that the Iraq War came to an end.