Rabbi Menachem Mendel Yosef Zaks (1898–1974), universally known as Rabbi Mendel Zaks, was a prominent Lithuanian-American Orthodox rabbi and Rosh Yeshiva (head of school). He is best remembered as the primary successor and son-in-law of Rabbi Yisrael Meir Kagan (the Chofetz Chaim), and for his monumental efforts in saving the remnants of the world-famous Raduń (Radin) Yeshiva during the Holocaust and rebuilding it in the United States.

Early Life and Marrying Into the Dynasty

• Prodigy of the Great Yeshivas: Born in Šiluva, Lithuania, Reb Mendel was recognized early on for his photographic memory and staggering intellectual capacity. He studied in the premier institutions of the pre-war era, including the Slabodka Yeshiva (Knesses Beis Yitzchok).

• Studying under Sages: He studied closely under the legendary Rabbi Meir Simcha of Dvinsk (the Or Sameach) and actually helped edit and print his masterful biblical commentary, the Meshech Chochmah.

• The Chofetz Chaim’s Choice: He eventually transitioned to the Radin Yeshiva, where his brilliance caught the eye of the aging Chofetz Chaim. In 1922, Reb Mendel married Feiga Chaya Kagan, the youngest daughter of the Chofetz Chaim. By entering the family, he immediately became the right-hand man to his father-in-law in both yeshiva administration and global communal leadership.

Leadership of the Radin Yeshiva

Following the passing of the yeshiva’s brilliant primary lecturer, Rabbi Naftoli Trop, in 1928, and the death of the co-Rosh Yeshiva, Rabbi Baruch Feivelson, in 1933, Reb Mendel became the sole, undisputed Rosh Yeshiva of Radin.

Under his stewardship, the yeshiva thrived, boasting over 400 advanced students. He was known for his extreme devotion to his pupils, sitting with them for endless hours and tailoring his lectures to match their varying levels of intellectual growth.

War, Escape, and the American Transition

The outbreak of World War II in 1939 shattered the Torah centers of Eastern Europe. When the Soviet Union and Nazi forces encroached on Poland, Reb Mendel orchestrated the evacuation of the Radin Yeshiva to Vilna, Lithuania.

Through immense effort, Reb Mendel managed to secure passage out of Europe, arriving in New York in 1941. Sadly, the students and townspeople left behind in Radin who could not escape were brutally massacred by the Nazis.

Upon reaching the safety of the United States, Reb Mendel did not wallow in grief. In 1943, he gathered the scattered survivors of his yeshiva and officially re-established Yeshivat Chofetz Chaim of Radin in New York City (which later relocated to Suffern, New York).

Academic Legacy at Yeshiva University

In 1946, Reb Mendel accepted an invitation to join the faculty of the Rabbi Isaac Elchanan Theological Seminary (RIETS), the rabbinical school of Yeshiva University.

For nearly three decades, he served as a senior Rosh Yeshiva and Bochen (the head admissions examiner) at the institution. He served as an invaluable bridge for thousands of American-born students, giving them direct, authentic exposure to the classic traditions, ethical nuances, and rigorous academic standards of the pre-war Lithuanian Torah giants.

Later Years and Descendants

Reb Mendel retired from teaching later in life and moved to Jerusalem, where he passed away in 1974 at the age of 76.

His legacy of scholarship was carried forward by his sons, who became formidable rabbinic figures in their own right:

• Rabbi Gershon Zaks: Succeeded his father as the Rosh Yeshiva of the American branch of the Radin Yeshiva until his passing in 1989.

• Rabbi Hillel Zaks: A legendary Torah scholar in Israel who served as a Rosh Yeshiva in the Slabodka Yeshiva of Bnei Brak and later founded the prominent Yeshivas Knesses Hagedolah in Kiryat Sefer (passing away in 2015).