Joseph August Jean Polak (also known as Jo) was one of the best chess players in Amsterdam. At the age of fifteen, under his father’s supervision, he took part in tournaments in Valkenburg. Soon after he became a member of the Amsterdam chess club Het Oosten. After doing well at several tournaments, he joined the Vereenigd Amsterdamsch Schaak Genootschap (the Amsterdam chess association). In September 1941, it became illegal for Jews to belong to clubs. From that time on, Jewish chess players met on Sundays in Joubertstraat. Over time, fewer and fewer people came to these meetings, because participants had been arrested or gone into hiding. Joseph August Jean Polak was in hiding for about a year. His location was betrayed, and he was arrested and taken away to Westerbork. There he played his last game of chess.
L.G. Eggink en W.A.T. Schelfhout Partij verloren… Gedenkboek ter herinnering aan de schakers in Nederland, die tijdens de bezetting heengingen (Amsterdam 1947)
Joseph August Polak was married to Rosa Presser. On October 18th, 1943, they had a son, Frans Alexander that was born at Westerbork transit camp.
Record of birth certificates of the Westerbork municipality, currently at the archives of Gemeente Midden-Drenthe in Beilen