The Justice Department prepared a list of all German aliens, counting approximately 480,000 of them, more than 4,000 of whom were imprisoned in 1917–18. The allegations included spying for Germany, or endorsing the German war effort. Thousands were forced to buy war bonds to show their loyalty. The Red Cross barred individuals with German last names from joining in fear of sabotage. One person was killed by a mob; in Collinsville, Illinois, German-born Robert Prager was dragged from jail as a suspected spy and lynched. A Minnesota minister was tarred and feathered when he was overheard praying in German with a dying woman. Questions of German American loyalty increased due to events like the German bombing of Black Tom island and the U.S. entering World War I, many German Americans were arrested for refusing allegiance to the U.S. War hysteria led to the removal of German names in public, names of things such as streets, and businesses. Schools also began to eliminate or discourage the teaching of the German language.