At the stroke of noon on New Year's Day, 1899, the Spanish flag on the Governor-General's palace in Havana was lowered and the Stars and Stripes went up. Officially, the Spanish-American War was over. But for the soldiers of the medical corps in charge of the health of the American occupation forces, the "fighting" had just begun. For lurking on rooftops, in narrow alleyways, and in a thousand dark corners of the city was Yellow Jack, an enemy far mightier than Spain...