Yahrtzeit of Rabbi Avraham Ibn Ezra (1089-1164), famed biblical commentator. He was born in Tudela during the height of Spain's Golden Age. When anti-Semitism flared, he was forced to flee to Rome, and later to Egypt. He also wrote dozens of books on astronomy, astrology and mathematics.
Adar 1 is also the yahrtzeit of Rabbi Shabsai HaKohen Katz (1622-1663), author of a classic commentary on the Code of Jewish Law (Shulchan Aruch). Katz is known popularly as the Shach, an acronym of his commentary, "Sifsei Kohen." He lived in Poland where he was forced to flee from the Cossack pogroms. The Shach died at age 41 in Germany.