In 1918, while the world was at war, mankind was stalked by a killer using neither bullets nor poisonous gas, yet claiming forty million more casualties than the war. Termed the “Spanish flu,” it did not begin in Spain; and unlike previous flu epidemics, it targeted not the young or the old but adults with healthy immune systems. In twenty-four weeks, it killed more people than AIDS has killed in twenty-four years - and more people in a year than the Bubonic Plague killed in a century. “Waging war” at home and in the trenches, Spanish flu tipped the victory to the Allies simply by reaching Germany and Austria before Britain and the United States. Learn about a modern pandemic that changed medicine and laid the foundation for World War II.