It's this portion of the book, too, that's most disturbing in its description of how devastating smallpox was to virgin populations. A trader touching on the coast of Alaska in 1787 finds a village with several large boats on the beach. Expecting to find many natives, he finds only three men, three women, and seven children, some of whom bore the tell-tale signs of smallpox. A few years later, when George Vancouver was exploring the Northwest Pacific coast, he noted the abandoned villages strewn with discarded human bones, the few remaining survivors clearly marked by the pox.

It's been a long time since smallpox last walked this earth. So long that we forget how devastating it could be. In Pox Americana Elizabeth Fenn has given us a timely reminder of its power and its horror. It wasn't for nothing that Washington called it, "this, our greatest Enemy."