Ernst Cahn was a son of Salomon Cahn and Rosa Katzenstein. He married in 1914 and had two children who survived the war. He lived with his family from 1924-1928 in Amsterdam. In 1936 he returned to the Netherlands, to Huizen, from Germany because of the persecution of the Jews.
Ernst Cahn co-owned ice-cream parlour Koco in the Van Woustraat in Amsterdam with business partner Alfred Kohn. On Wednesday, 19 February 1941, a patrol of the Nazi Ordnungspolizei carried out a raid on the ice-cream parlour. Inside, a bunch of heavies were waiting for them, as they had expected an attack by pro-Nazi Dutchmen. Ammonia was squirted from the ice-cream parlour. Ernst Cahn and Alfred Kohn were arrested and condemned by a Nazi court after they endured serious physical abuse in Amsterdam and in the penal barrack in Scheveningen's prison. Ernst Cahn was condemned to death. He was executed on 3 March 1941. Ernst Cahn was the first person in the Netherlands to die in front of a firing squad.
B. Braber, Zelfs als wij zullen verliezen. Joden in verzet en illegaliteit in Nederland 1940-1945 (Amsterdam, 1990), 67, 144-145;
L. de Jong, Het Koninkrijk der Nederlanden in de Tweede Wereldoorlog. Deel 4. Mei ’40-Maart ’41 (Den Haag 1972), 889, 912;
J. Presser, Ondergang. De vervolging en verdelging van het Nederlandse jodendom 1940-1945 Deel II (Den Haag 1965), 84-85
R. Fuks-Mansfeld (red.), Joden in Nederland in de twintigste eeuw. Een biografisch woordenboek (Utrecht 2007) 39