(born 3 December 1888 – died 25 July 1959), also known as Isaac Herzog, was the first Chief Rabbi of Ireland, his term lasting from 1921 to 1936. From 1937 until his death in 1959, he was Ashkenazi Chief Rabbi of the British Mandate of Palestine and of Israel after its independence in 1948.
abbi Herzog was born in ?om?a, Poland, and moved to the United Kingdom with his family in 1898, where they settled in Leeds. His initial schooling was largely at the instruction of his father, Joel Leib Herzog, who was a rabbi in Leeds and then later in Paris.
After mastering Talmudic studies at a young age, Yitzhak went on to attend the Sorbonne and then later the University of London, where he received his doctorate. His thesis, which made him famous in the Jewish world, concerned his claim of re-discovering Techelet, the type of blue dye once used for the making of Tzitzit.
Rabbi Herzog served as rabbi of Belfast from 1916 to 1919 and was appointed rabbi of Dublin in 1919. He was a fluent speaker of the Irish language. He was Chief Rabbi to what (from 1922) became the Irish Free State. He was known as "the Sinn Féin Rabbi" He went on to serve as Chief Rabbi of Ireland between 1922 and 1936, when he immigrated to Palestine to succeed Rabbi Abraham Isaac Kook as Ashkenazi Chief Rabbi upon his death.
Rabbi Herzog's descendants have continued to be active in Israel's political life. Chaim Herzog, the rabbi's son, was a general in the Israel Defense Forces and later became ambassador of Israel to the UN and President of Israel. His other son Yaakov Herzog was an influential figure in Israeli politics between 1948 and his untimely death in 1972. During that period he served as Israel's ambassador to Canada and later as Director General of the Prime Minister's Office. He also accepted an offer to become Chief Rabbi of the British Commonwealth but due to ill health never took up that role. Currently, his grandson Isaac Herzog is a member of the Knesset, Israel's parliament. He has previously served as housing and tourism minister and minister of welfare.
In May 1939, shortly before the Second World War, the British put out the White Paper of 1939 restricting Jewish immigration to Palestine. After leading a procession through the streets of Jerusalem, with an unusually united Jewish following from all sects, on the steps of the Hurva Synagogue he turned and said: We cannot agree to the White Paper. Just as the prophets did before me, I hereby rip it in two. Some 40 years later, on 10 November 1975 Ambassador Herzog repeated his father's gesture with the UN resolution that Zionism is equal to racism.
During the Second World War, Rabbi Herzog travelled with great risk to the US, and back, not before he was able to secure a meeting with Roosevelt. Roosevelt smiled and did not reply to the Rabbi's pleadings for a promise to help the Jews of Europe. His biographer records that several people noticed that his hair turned white when he left the meeting, which he perceived as a failure. Following this, he immediately returned home, missing the ride on a ship that was sunk by a U-boat, and taking what was said to be the last civilian ship to cross the Atlantic during the war.
After the war, Rabbi Herzog dedicated himself to saving Jewish children especially babies and bringing them back from their places of hiding throughout all of Europe, to their families or to Jewish orphanages. Many of these were hidden in Christian monasteries or by Christian families, and refused to return them. In his biography, he tells of the difficulties he had of meeting the Pope who avoided him, but did receive in the end assistance from the Vatican. In later years it was found that Pope John Paul was the contact who helped the rabbi out. However, defenders of Pope Pius XII have asserted that Herzog had maintained friendly relations with the pontiff during and after the WW2. In 1945, he stated: “The people of Israel will never forget what His Holiness and his illustrious delegates are doing for our unfortunate brothers and sisters in the most tragic hour of our history, which is living proof of Divine Providence in this world.” 
Rabbi Herzog was recognised as a great rabbinical authority, and he wrote many books and articles dealing with halachic problems surrounding the Torah and the State of Israel. Indeed, his writings helped shaped the attitude of the Religious Zionist Movement toward the State of Israel. Rabbi Herzog authored:
• Main Institutions of Jewish Law
• Heichal Yitzchak
• Techukah leYisrael al pi haTorah
• Pesachim uKetavim
• The Royal Purple and the Biblical Blue
• In 1958, Rabbi Herzog was awarded the Israel Prize, in Rabbinical literature.
• History of the Jews in Ireland
• History of the Jews in Northern Ireland
• Herzog (disambiguation)
• Shmuel Wosner
• List of Israel Prize recipients
1. "Herzog, Chaim (1918–1997)". Israel and Zionism. The Department for Jewish Zionist Education. Retrieved 5 November 2007.
2. Living History – A Memoir. New York: Pantheon Books. 1996. p. 6. ISBN 978-0-679-43478-8.
3. Living History – A Memoir. New York: Pantheon Books. 1996. p. 7. ISBN 978-0-679-43478-8.
4. Benson, Asher (2007). Jewish Dublin. Dublin: A&A Farmer Ltd. p. 22. ISBN 978-1-906353-00-1.
5. Lammfromm, Arnon (2009). Chaim Herzog, HaNasi HaShishi (Chaim Herzog, the Sixth President) (in Hebrew). Jerusalem: Israel State Archives. p. 296. ISBN 978-965-279-037-8.
6. On Popes and Jews, Akiba Zimmerman, Hazofe newspaper archive (Hebrew). It is said as an urban legend, that one tactic he had for proving which children were Jewish, although still in denial or mostly afraid of the monastery staff, would be to call out the Shema Yisroel and Jewish children would instinctively cover their eyes along with him.
7. Pius XII website
8. "Israel Prize recipients in 1958 (in Hebrew)". Israel Prize Official Site. Archived from the original on 17 January 2010.
Yoel Leib Halevy Herzog (Gercek) ? ?
Gmina ?om?a, Podlachia, Poland
Son of Herszk (Naftali) Herzog (Gercek) and Sora Herzog (Gercek)
Husband of Liba Miriam Herzog (Gercek)
Father of Yitzchak-Isaac ???? Ha-Levi Herzog and Esther Goldberg
Brother of Rachel Herzog (Gercek)
April 11, 1895
1942 (47) (murdered by the nazis)
Son of Sine Simche Herzog and Ite Lieba Herzog
Husband of Ruchel Feigel Silberfeld
Father of Abraham Herzog and Dora Herzog
Izak Mordechai Herzog
October 7, 1897
Cracow, Lesser Poland, Poland
October 1944 (47) (murdered by the nazis)
Son of Sinai Simche Herzog and Ite Lieba Herzog
Husband of Ester
Josef Jakob Herzog ? ?
Krakow, Kraków County, Lesser Poland Voivodeship, Poland
1942 (17) (murdered by the nazis)
Son of Izak Mordechai Herzog and Ester Herzog
Brother of Lena Lea Rosner