Yahrtzeit of Rabbi Yitzhak HaLevi Herzog (1889-1959), Chief Rabbi of Ireland and later the Chief Rabbi of Israel during the years of Israeli independence. His father was the Chief Rabbi of Paris, and his son, Chaim Herzog, was later president of Israel. Rabbi Herzog studied Oriental languages at the Sorbonne in Paris, and classics and mathematics at the University of London. His doctoral dissertation claimed that the Murex snail is the source for Techelet, the long-lost blue dye used for making tzitzit. After World War II, Herzog went on a rescue mission to redeem Jewish children from the churches and monasteries where they had been hidden during the war. Rabbi Herzog authored a book of talmudic discourses, Divrei Yitzhak.