During World War II, the US Public Health Service (USPHS) administered health care to 19 000 enemy aliens and Axis merchant seamen interned by the Justice Department through its branch, the Immigration and Naturalization Service (INS). The Geneva Prisoners of War Convention of 1929, which the United States applied to civilian internees, provided guidelines for belligerent nations regarding humanitarian treatment of prisoners of war, including for their health. The INS forged an agreement with the USPHS to meet these guidelines for the German, Italian, and Japanese internees and, in some cases, their families. Chronic shortages and crowded camps continuously challenged USPHS administrators. Nevertheless, the USPHS offered universal access to care and provided treatment often exceeding care received by many American citizens.