Betje-Hadassah Polak was born in 1921 in Haarlem, the Netherlands to parents Emiel-Yehuda and Else. Emiel was a hat sales agent, and the family lived comfortably. Betje had a younger sister and brother, Bernadina-Dini (b. 1923) and Jap-Jacob (b. 1926). The three children went to the local school. The family had Zionist affiliations, and Dini was active in the "Maccabi" youth movement.
In 1939, Betje went to visit her maternal grandparents in Manchester, England. When the war broke out, Emiel asked Betje to return home. Betje came back to the Netherlands and commenced laboratory studies, in the course of which she met her future husband, Ernst-Menahem Rozen, who had fled with his parents from Berlin to the Netherlands in 1938. Betje completed her studies, but was prevented from taking her final exams by of the German invasion of the Netherlands in May 1940. Betje joined a Hachshara (pioneer training) program run by the Hechalutz movement in Elden, southern Holland, with a view to immigrating to Eretz Israel (Mandatory Palestine). There, she learned about plant life and how to milk cows. Dini also joined a Hachshara scheme in Elden.
Following the occupation, Dutch Jews were subjected to restrictions, and were not permitted to visit public places. They were marked, had to hand in their bicycles, and their freedom of movement was curbed. Arrests and deportations to the East began in the summer of 1942. Members of the Hachshara in Elden, Dini included, were caught by the Germans and incarcerated in the Westerbork transit camp in the Netherlands. Dini obtained an immigration permit for Eretz Israel ("certificate"), and several months later she was sent to Bergen-Belsen, where she was housed in the "Dutch camp" and was amongst those designated for a prisoner swap with German POWs.
In February 1943, the Polaks received a deportation order. On the initiative of Betje's teacher, Gardiena-Dien Hinlopen and her husband Frans, Betje, her parents and her brother Jacob were hidden in different places with the assistance of the Dutch resistance, and were moved to new hiding places from time to time. Betje's boyfriend Ernst-Menahem also appeared at one of the hiding places, and they stayed there together with other youngsters for some 3 months. After that, Betje found a new hiding place, and Menahem searched for a different one for himself. He met a young Dutchman who had received an order from the Germans to report to Rotterdam for deportation to forced labor in the East. Menahem persuaded him to give him the order and his ID card so that he could report in his stead. Menahem shortened his hair so as to look more like the photograph on the ID card, and went to Rotterdam. He was attached to a group that was sent to work in Lithuania. They passed through Berlin on their way. When they reached Berlin, they were asked if any of them was proficient in book-keeping. Menahem volunteered, and was kept in Berlin. He was transferred to a factory that manufactured locomotives, where most of the workers were foreigners. Menahem survived the war in Berlin. Betje, her parents and her brother Jacob also survived. In 1944, Dini was part of a prisoner swap and reached Eretz Israel.
After liberation, Menahem joined the stream of refugees and set out on foot for the Netherlands, eventually reuniting with Betje. They got married in October 1945 and in late July 1946, they left Marseille port on the "Yagur" bound for Eretz Israel. They were intercepted by the British and sent to a transit camp in Cyprus. After their release in December 1946, they reached Eretz Israel. They joined a Hachshara group in Sde Nehemiah, and a year letter, they settled in Kibbutz Dovrat. Betje's parents and brother eventually followed.
The rescuers of Betje, her parents and brother were later recognized by Yad Vashem as Righteous Among the Nations: Frans and Alberta-Gardiena Hinlopen, Maria Van Dijk, Cornelis and Amanda Dekker, Henriette and Kleys Kroon, and Pietje Besse.In 2011, the forged ID papers of Betje-Hadassah and Menachem displayed here, were donated to the Yad Vashem Archives as part of the "Gathering the Fragments" project.