Yaakov Yisrael Kanievsky, known as The Steipler or The Steipler Gaon (1899–1985), was a rabbi, Talmudic scholar, and posek ("decisor" of Jewish law).
He was born in the Ukrainian town of Hornostaypil, from which his appellation, "the Steipler", was later derived. He was the son of Chaim Peretz, who was a Chernobyl Chassid and the local shochet. Around the age of 11, Kanievsky entered the Novardok yeshiva, studying under its famed dean, Rabbi Yosef Yoizel Horowitz.
Having progressed rapidly and gained a reputation as a Talmid Chacham, around the age of 19 he was sent by Horowitz to set up a branch of the yeshiva in Rogochov. However, the Bolshevik Revolution was in full swing and Kanievsky was conscripted into the Red Army. In spite of the harsh conditions, he continued to strictly observe all the mitzvot.
Once, during his army stint, Kanievsky was Court-martialled for "failing to do his duty" when there was a possibility of breaking the Sabbath. He was forced to walk between two rows of soldiers who were ordered to beat him as he passed. In later years, Kanievsky remarked that the satisfaction he had enjoyed for making a stand for his religious convictions was an achievement never again equaled for the rest of his life.
After serving under arms for some time, Kanievsky managed to get discharged. He decided to move to Białystok in Poland in order to continue learning Torah unhindered from Communist interference. There, he studied under Rabbi Avrohom Jofen.
In 1925, Kanievsky published his first sefer ("work"), Sha'arei Tevunah ("gates of understanding"). This was received with great acclaim, and the work eventually reached Rabbi Avraham Yeshayahu Karelitz (known as the Chazon Ish) in Vilna. Without even meeting him, Karelitz decided that the author of such a work was worthy of marrying his sister Miriam.
Kanievsky was then appointed rosh yeshiva of the Novarodok yeshiva in Pinsk. In 1934, he relocated to Bnei Brak in the British Mandate of Palestine, where his brother-in-law Karelitz had already been living for a year and a half. For many years he was head of two yeshivas there. Though known as a world-class scholar, Kanievsky shunned publicity and lived in humble surroundings, teaching, writing and devoting himself to Torah and good deeds.
Over 150,000 mourners attended Kanievsky's funeral in 1985. His son, Rabbi Chaim Kanievsky, following in his father's path, is a well-known Haredi rabbinical authority.He also has a daughter who currently lives in Bnei Brak.
The Steipler wrote many works, his magnum opus being the multi-volume Kehillot Yaakov ("assembly of Jacob"), containing his unique analysis of most of the tractates and concepts of the Talmud. He also authored Birkath Peretz (on the Pentateuch) and Chayei Olam.There are several volumes of letters, known as Karyana D’Igarata, and several volumes written by a disciple, Rabbi A Horowitz, describe his daily life. These are known as Orchot Rabbeinu.