Positions held After working as a school librarian, Kranzler joined the faculty of
Queensborough Community College (QCC) of the
City University of New York in 1969, and was a professor in the library department until his retirement in 1988. He was one of the founders and the first director of QCC's Holocaust Resource Center and Archives (now known as the Harriet and Kenneth Kupferberg Holocaust Center). He served as scholar-in-residence in numerous congregations, college campuses, and centers, including the Spanish-Portuguese Synagogue (under Rabbi
Marc D. Angel) in Manhattan; Kodima Synagogue in Springfield, Massachusetts (under his brother-in-law Rabbi Alex Weisfogel); and the Ohio State University Holocaust Center (under Professor
Saul S. Friedman). From October 2002 to January 2003, Kranzler was a Baron Friedrich Carl von Oppenheim Research Fellow for the Study of Racism, Antisemitism, and the Holocaust at
Yad Vashem's International Institute for Holocaust Research; the title of his research project was "A Comparative Study on the Worldwide Rescue Effort by Orthodox Jewry During the Holocaust Within the Context of Rescue in General".
Research Kranzler became the leading historian on the subject of Jews aiding and rescuing the Jews during
the Holocaust, and was among the first to document the efforts of
Orthodox Jewish organizations, such as the
Vaad Ha-hatzala and
Agudath Israel. Historian
Alex Grobman referred to him as "the pioneer of research on Orthodox Jewry during the war." Kranzler's books
Solomon Schonfeld: His Page in History, co-authored with Gertrude Hirschler, and his later ''Thy Brother's Blood
(1987) were the first to focus on this area. He wrote a paper, "Orthodox Ends, UnOrthodox Means", for American Jewry during the Holocaust'' (1983), a report organized by the
American Jewish Commission, led by
Arthur J. Goldberg. Kranzler lectured on the subject in America, Israel, Europe and the Far East. He interviewed and recorded over a thousand people, including some of the major Jewish rescuers, such as
Hillel Kook (also known as
Peter Bergson),
George Mantello, Rabbi
Solomon Schonfeld,
Julius Kuhl, and close family and associates of rescuers no longer alive, including Rabbi
Michael Ber Weissmandl and
Recha Sternbuch. He established a research archive of about a million pages and interviews (mostly audio on about 1,000 cassettes) which were at his Brooklyn home. By 1978 the archive held over 10,000 documents on Jewish residents of Shanghai. After Dr. Kranzler's death the archive was transferred to Yad Vashem. In his book ''Thy Brother's Blood: The Orthodox Jewish Response During the Holocaust'' (1987), Kranzler argued that more lives could have been saved if American-Jewish leaders had lent more support to efforts in Europe to halt the deportations, including the attempts, in
Slovakia and
Hungary, to bribe and/or pay ransom to the SS. Criticizing the book's factual accuracy,
Efraim Zuroff described it as "an extremely one-sided polemic" and "a popular invective of limited scholarly value". In the view of historian Robert Moses Shapiro, the book's defects, particularly its bitter tone and poor editing, undermined its "important and gripping story". The mid-1944 grassroots protests in Switzerland, including street demonstrations, Sunday sermons and the
Swiss press campaign of about 400 headlines about the atrocities were triggered by George Mantello making public a summary of the Auschwitz Report (
Vrba–Wetzler report) is the subject of Kranzler's book ''The Man Who Stopped the Trains to Auschwitz: George Mantello, El Salvador and Switzerland's Finest Hour'' (2000), which has a foreword by
Joe Lieberman. The Vrba–Wetzler report, written by two Auschwitz escapees,
Rudolf Vrba and
Alfred Wetzler, and distributed mostly by the
Bratislava Working Group, provided a detailed account of the mass murder taking place inside the
Auschwitz concentration camp. Kranzler was convinced that Mantello's campaign to publicize the report led to the stopping of the mass transports of Jews from Hungary to Auschwitz in July 1944, and enabled the
Raoul Wallenberg mission and other important initiatives in Hungary and elsewhere. The manuscript won the 1998 Egit Prize from the
Histadrut for the best manuscript on the Holocaust. During his fellowship with
Yad Vashem's International Institute for Holocaust Research in 2002–2003, Kranzler engaged in a research project entitled "A Comparative Study on the Worldwide Rescue Effort by Orthodox Jewry During the Holocaust Within the Context of Rescue in General." ==Recorded talks==