WASHINGTON — The baby had so many pustules ravaging his face he could barely open his right eye, a photograph that left the president, national security adviser and close aides nearly speechless with horror. A global pandemic had begun in a hospital in Oklahoma City. Doctors soon diagnosed smallpox, a virulent, deadly and disfiguring infection that had disappeared from the planet two decades before. What would the president do? This was the scenario that a cast of Washington power players sought to tackle over two days at Andrews Air Force Base in June 2001. The exercise, code-named Dark Winter, has passed into Washington lore as the first high-profile alarm of the dire consequences of a pandemic. For months after Dark Winter, advisers to President George W. Bush attempted to come to grips with what they predicted would happen in such a contagion: overwhelmed hospitals, broken medical supply chains and frenzied grocery buying.  Three months later, the 9/11 attacks made