Commissioned to illustrate the League of Nations charter. When the German Army invaded Poland in 1939 Szyk went to the United States in an attempt to sway public opinion against the Nazis. He now began to use his considerable skills within the genre of political caricature. His work appeared in the New York Post, the New York Times and Collier's and he became known as "Franklin Roosevelt's soldier with a pen".
Szyk's drawings were very important for the American war propaganda. In recognition for his services in the fight against Nazism, Fascism and the Japanese aggression, Eleanor Roosevelt, the wife of President F. D. Roosevelt, said of him: "This is a personal war of Szyk against Hitler, and I do not think that Mr. Szyk will lose this war!" She also dubbed him "one man army", which became Szyk's famous nickname. Szyk himself often called himself "soldier in art". Other famous quotations by him are: "Art is not my aim, it is my means", and "I am but a Jew praying in art."