Isaac Breuer (Hebrew: יצחק ברויאר; 1883–1946) was a rabbi in the German Neo-Orthodoxy movement of his maternal grandfather Samson Raphael Hirsch, and was the first president of Poalei Agudat Yisrael.
He attended Hirsch's Realschule school, and received rabbinical ordination at age 20 from his father's yeshivah.
[citation needed] In 1936 Breuer immigrated to Jerusalem, where he led Poalei Agudat Yisrael and represented it before the Peel and Anglo American Commissions.
His son-in-law Hermann Merkin helped to establish the Isaac Breuer College of Hebraic Studies (IBC program) at Yeshiva University in his memory.
Indeed, Breuer envisioned a Messianic Torah state in the land of Israel, and could not abide the idea of "reunification of land and nation" coming to pass through the agency of secular Zionist forces in the form of a secular state.