In the last hard days of World War I, just two weeks before world powers agreed to an armistice, a doctor wrote a letter to a friend. The doctor was stationed at the US Army’s Camp Devens west of Boston, a base packed with 45,000 soldiers preparing to ship out for the battlefields of France. A fast-moving, fatal pneumonia had infiltrated the base, and the ward he supervised was packed full of desperately sick men.

“Two hours after admission they have the mahogany spots over the cheek bones, and a few hours later you can begin to see the cyanosis extending from their ears and spreading all over the face,”