The penal colony of Bagne de Cayenne, commonly known as Devil's Island (Île du Diable), was a famous prison in the 19th and 20th century. It operated at several locations in French Guiana. Opened in 1852, it was notorious for being used for internal exile of French political prisoners during that period, the most famous of which was Captain Alfred Dreyfus. It is also known for its harsh treatment of criminals, who were deported there from all parts of the French empire. The system was closed down in 1953.
The penal colony at Devil's Island, where Alfred Dreyfus had been falsely imprisoned, was no longer operative. But the French had other ways of letting Jews know they weren't popular. Jacob Dreyfus, conscious of his ancestor's misfortune, had always known this, and was not surprised when he was stuck with the most dangerous assignment that was puzzling the police force.