Zedekiah was the last king of the royal house of David to reign in the Holy Land. He ascended the throne in 434 BCE, after King Nebuchadnezzar of Babylonia (to whom the kingdom of Judah was then subject) exiled King Jeconiah (Zedekiah's nephew) to Babylonia . In 425 BCE Zedekiah rebelled against Babylonian rule, and Nebuchadnezzar laid siege to Jerusalem (in Tevet 10 of that year); in the summer of 423 BCE the walls of Jerusalem were penetrated, the city conquered, the (first) Holy Temple destroyed, and the people of Judah exiled to Babylonia. Zedekiah tried escaping through a tunnel leading out of the city, but was captured; his sons were killed before his eyes, and then he was blinded. Zedekiah languished in the royal dungeon in Babylonia until Nebuchadnezzar's death in 397 BCE; Evil Meroduch -- Nebuchadnezzar's son and successor -- freed him (and his nephew Jeconiah) on the 27th of Adar, but Zedikiah died that same day.
On the 27th of Adar I, 5752 (Monday, March 2, 1992), the Lubavitcher Rebbe, Rabbi Menachem Mendel Schneerson, suffered a disabling stroke while praying at the gravesite of the previous Rebbe, Rabbi Yosef Yitzchak of Lubavitch. On the same date two years later, the Rebbe lost consciousness following another stroke; three months later, on the 3rd of Tammuz 5754 (June 12, 1994), the Rebbe's soul ascended on high, orphaning a generation.
Links:
A Gathering With the Rebbe
A Silence Louder Than Words
Everyone a Tzaddik: Miracles, Transmission and Ascent
On the Shabbat that falls on or before the 1st of Nissan, a special reading called "Hachodesh" (Exodus 12:1-20) is added to the regular Shabbat Torah reading. Hachodesh recounts G-d's historic communication to Moses in Egypt on the 1st of Nissan (2 weeks before the Exodus) regarding the Jewish calendar, the month of Nissan and the Passover offering.
Links: The Reading for Hachodesh
From the teachings of the Chassidic masters on Hachodesh
About the Jewish calendar
Haftorah in a Nutshell
This Shabbat is Shabbat Mevarchim (“the Shabbat that blesses" the new month): a special prayer is recited blessing the Rosh Chodesh ("Head of the Month") of the upcoming month of Nisan, which falls on Tuesday of the following week.
Prior to the blessing, we announce the precise time of the molad, the "birth" of the new moon. See molad times.
It is a Chabad custom to recite the entire book of Psalms before morning prayers, and to conduct farbrengens (chassidic gatherings) in the course of the Shabbat.
Links: Shabbat Mevarchim; Tehillim (the Book of Psalms); The Farbrengen