During the Seven Years' War they assisted Frederick the Great in debasing the Saxonian currency[1] and spreading the Ephraimiten, not only in Saxony, but also in Silesia, Poland, Bohemia and Courland.
Together with his son in law David Friedlander, Itzig was appointed to lead a committee which was to discuss ways to improve the Jewish civil and social standing in Prussia, which led to the removal of many restrictions.
He funded early members of the Haskalah secular movement, including Rabbi Israel of Zamosch (Moses Mendelssohn's teacher), Samuel Rominow (an Italian Jewish artist) and Isaac Satanow.
His wife Miriam Wulff's ancestors included Rabbi Moses Isserles of Kraków and Joseph ben Mordechai Gershon.
One of them was Lea (née Solomon), mother of Felix Mendelssohn and Fanny Hensel, a pianist and composer.