Rabbeinu Mendel Rosenbaum was born in 1782 in Theilheim (today a municipality of Würzburg). Although he was very learned, Rav Mendel did not seek a rabbinical post, rather he supported his family through peddling wares. His business ventures were successful, and eventually Rav Mendel was able to delegate his business affairs to others and spend more time learning and teaching Torah. He moved to Zell (Am Main – a town closer to Würzburg) and later purchased a building to house a Yeshiva. He hired Rav Eliezer Bergmann (student of Rav Avraham Bing, later to become Rav Mendel’s son-in-law) to teach his own children. Rav Mendel’s influence increased and eventually he opened a Yeshiva together with his sons. Among the disciples of the yeshiva were Rav Moshe Weiskopf, Rav Yitzchak Strauss, and many of the Würzberger Rav’s children. Rav Mendel also befriended government officials and petitioned for many issues on behalf of the kehillos of Bavaria. When he turned 80, he retired and spent his time learning and davening. Rav Mendel Rosenbaum passed away in 1868.