On the 13th of Tammuz of 1927, the sixth Lubavitcher Rebbe, Rabbi Yosef Yitzchak Schneersohn, received the documents authorizing his release from a sentence of exile to Kastroma in the interior of Russia.
The Rebbe was actually notified of his release on Tammuz 12, but since that day was a legal holiday, the Certificate of Release freeing him to travel home was issued only the next day.
Thus both the 12th and 13th of Tammuz are celebrated as a “festival of liberation” by the Chabad-Lubavitch community.
(chabad.org)
