In spring of 1918, World War I was underway, and troops at Fort Riley, Kansas, found themselves felled by influenza. By the summer of 1918, the second wave struck as a highly contagious and lethal epidemic and within weeks exploded into a pandemic, an illness that travels rapidly from one continent to another. It would impact the course of the war, and kill many millions more soldiers than warfare itself. Of all diseases, the 1918 flu was by far the...