Avraham-Aharon Kastenbaum was born in Drohobycz on September 7th, 1896 (29th of Elul). He studied in the Yeshiva of the Gaon Rabbi Avraham Kitaigrodsky and in the seminary of the Drohobycz spiritual Hasidic leaders of the Shapira dynasty, who supported the urgent settlement of the Land of Israel and held Zionist meetings in their Beit Midrash.
He served in the Austrian army during the First World War. His mother went to great lengths to deliver him kosher food. The Zionist ideas were reinforced for him during this period of time - Jewish soldiers’ blood was spilled for both of the fighting sides, but none of it for the people of Israel and the Land of Israel.
In the early 1920s, Avraham immigrated to Israel via Vienna with a group of religious pioneers from Poland. With Rabbi Yeshayahu Shapira (“The Pioneer Rebbe”), Yeshayahu Bernstein and other distinguished members, he was one of the founders of the Hapoel Hamizrachi movement. He was the head of the movement's agricultural center and was one of the founders of many of the villages and of "modern" yeshivas, such as Moshav Sde Ya'akov, Kfar Yavetz, Kibbutz Yavne, Kfar Hasidim, Kfar Haroeh, Kfar Avraham, Kfar Pines (which was the first “hesder” yeshiva), the high school yeshiva in Kfar Haroeh (the first yeshiva of the Bnei Akiva movement), the "Netiv Meir" yeshiva high school (in Jerusalem), the "Torah U Mlacha” (“Torah and Crafts") Technological Yeshiva (in Petach Tikvah).
Kastenbaum coined the name "Bnei Akiva" for our youth movement in 1929.
In 1932 David Ben-Gurion and Avraham Kastenbaum signed an extensive cooperation agreement between the Histadrut (General Federation of Hebrew Workers) and the Hapoel Hamizrachi Federation. This agreement laid the foundation for a fruitful partnership which later became known as the "historic alliance" between Mapai (which was a center-left political party, the dominant force in Israeli politics for many years) and the Mafdal (National Religious Party).
Together with Rabbi Moshe Zvi Neria he proposed the name "Elitzur", for the Religious Sports Association. Due to his organizational skills, extensive knowledge, dedication to his missions and his charming personality Avraham-Aharon Kastenbaum held many positions: Member of the World Mizrachi Movement, Hapoel Hamizrachi, and the treasurer of the movement; Member of the Board of Directors of the Jewish National Fund; Extensive involvement in many Zionist congresses; A member of the founding board of the Talmudic Encyclopedia and much more. The heavy workload and the many difficult struggles overwhelmed him and he passed away in his prime, on the 12th of Nissan, 1956 (March 24th, 1956).
The results of his many deeds can be seen throughout The Land of Israel – this is the beautiful face of Religious Zionism.