In the 1950s and the 1960s, he established European charities in his daughter's name and founded the trust which preserved his family's wartime hiding place, the Anne Frank House, in Amsterdam.

[2] Otto studied economics in Heidelberg from 1908 to 1909 and had a work experience placement at Macy's Department Store in New York City thanks to a college friend his age, Nathan Straus Jr.

He and his two brothers were drafted for military service in August 1915 and after training at a depot in Mainz, he served in an artillery unit on the Western Front in which most soldiers were mathematicians and surveyors.

In 1917, he was promoted in the field to lieutenant and served at the Battle of Cambrai, where two of his French cousins, Oscar and Georges, were killed in action.

[7] Frank worked in the bank that his father initially ran, which subsequently he and his brothers inherited until its collapse in the early 1930s.

In late October 1944, Margot and Anne were transferred from Auschwitz to the Bergen-Belsen concentration camp where they died[9] of typhus.

In August 1933, they relocated to Aachen, where his mother-in-law, Rosa Holländer resided, in preparation for a subsequent and final move to Amsterdam in the Netherlands.

In 1938, Otto Frank started a second company, Pectacon, which was a wholesaler of herbs, pickling salts, and mixed spices, used in the production of sausages.

Ten days later, when Nazi Germany and Fascist Italy declared war on the United States, the visa was canceled.

At the age of 53, when the systematic deportation of Jews from the Netherlands started in the summer of 1942, Otto Frank took his family into hiding on 6 July 1942 in the upper rear rooms of the Opekta premises on the Prinsengracht, behind a concealing bookcase.

The day before, his older daughter, Margot, had received a written summons to report for so-called labour duty in Germany, and Otto immediately decided to move the family to safety.

After being imprisoned in Amsterdam, the Jewish prisoners were sent to the Dutch transit camp of Westerbork and finally, in September, to Auschwitz-Birkenau, where Frank was separated from his wife and daughters.

After the liberation of Auschwitz, Otto Frank wrote to his mother in Switzerland, where she had fled in 1933 when Hitler came to power.

Kugler and Kleiman and especially Miep and her husband and Bep Voskuil provided us with everything for two whole years, with incomparable devotion and sacrifice and despite all danger.

He was persuaded that Anne's writing shed light on the experiences of those who suffered persecution under the Nazis and was urged to consider publishing it.

He typed out the diary into a single manuscript, editing out sections he thought too personal to his family or too mundane to be of interest to the general reader.

The manuscript was read by Dutch historian Jan Romein, who reviewed it on 3 April 1946 for the Het Parool newspaper.

[28] In response to a demolition order placed on the building in which Otto Frank and his family hid during the war, he and Johannes Kleiman helped establish the Anne Frank Foundation in Amsterdam on 3 May 1957, with the principal aim to save and restore the building so it could be opened to the general public.

[29] For the rest of his life, Otto Frank dedicated himself to the publication of the diary and the ideals his daughter had expressed in it.

In 1959, Frank "lodged a criminal complaint on the grounds of libel, slander, defamation, maligning the memory of a deceased person and antisemitic utterances"[35] against two members of the right-wing Deutsche Reichspartei, Lothar Stielau and Heinrich Buddeberg, who had dismissed the diary as a work of fiction.

In 1976, Nazi sympathizer Ernst Römer accused Frank of editing and fabricating parts of Anne's diary.

However, the BKA found that these parts were simply two scraps of paper not attached to the manuscript and clearly written in different handwriting.