Yaakov was born on January 14, 1927 in the Old City of Jerusalem to Shlomo and Haya (née Shneur, of Rishon LeZion), who had four children. He attended the Tachkemoni School, and in 1941 he moved to Kibbutz Ramat Yohanan, as part of a youth group, studying for four more years. He was trained in weaponry and field maneuvers, under the auspices of the Gadna and Hish corps.
He returned to Jerusalem, and in 1946, he joined Lehi. He trained others with light weapons, including exercises with machine guns and grenades, as well as field maneuvers. He participated in the battles for Jerusalem, including blowing up the Tanus House commercial center, attacking the Shahin House in Katamon, facing off against British armored units in Lifta, fighting in Der Yassin and battling for the Old City on the 14th of May and in July 1948. He was wounded at Notre Dame on 15 May 1948. After recovering, he returned to the Lehi camps and began training again. After Lehi was disbanded in Jerusalem, he enlisted in the IDF and was assigned to Battalion 68 in the Jerusalem Brigade. There he became a company commander, his combat troops coming from those who had recently made aliyah (Gahal). In November 1948, he was wounded once again, at the head of his company, in the offensive launched against the House of Yellow Shutters in Abu Tor. A year later, he was demobilized.
In the Six-Day War, he fought to liberate Jerusalem. In the Yom Kippur War, as a reserve soldier, he served for four months as the municipal officer of Ashdod.
In 1950, he began studying at the youth aliyah teachers’ seminary in Jerusalem. Once he graduated, he was hired at the Ayanot training farm. He served as an educator and instructor for a group of Yemenite youth, who had made aliyah through Operation Magic Carpet. During his reserve duty, he completed a course for physical education and Gadna, and so he became the Gadna officer of Ayanot. After some years had passed, he left the filed of education and was hired to the editorial staff of the Hebrew Encyclopedia in Jerusalem, in an administrative capacity. In 1962, he completed a course for employment consultants, a field in which he worked until his retirement in 1990.
Starting in 1960, he studied at Tel Aviv’s Avshalom Institute, leading tours and lectures to educate people about the Land of Israel. He also studied public management at the Jerusalem College of Management.
In 1953, he married Rut “Yardena” Yifrach, whom he knew from Lehi. They live in Jerusalem and have three daughters and numerous grandchildren. As a pensioner, Yaakov volunteered to lead some tours and lectures at Beit Yair, educating students, police and soldiers about Lehi in Jerusalem and the city’s history in that era.