A visa to Cuba
According to news reports, Otto Frank tried to arrange for his family - wife Edith, daughters Margot and Anne and his mother-in-law - to go to Cuba or to the US.
He wrote to relatives, friends and officials during 1941 seeking their help, with limited success.
But the family did manage to secure one visa to Cuba, which was then cancelled in December 1941 after the Germans declared war on the US.
The family went into hiding in July 1942 and spent two years in a secret annex in a warehouse in Amsterdam before being found out and arrested by the occupying Nazis.
Anne Frank wrote her famous diary during the time in hiding – it has sold an estimated 75 million copies worldwide.