For a long time, historians were not at ease with the unpredictability of crisis mortality: "Epidemic disease, when it did become decisive in peace or in war, ran counter to the effort to make the past intelligible" (McNeill 1998). Yet, with hindsight-history is always about hindsight, and historical demography is no exception-these events, while they would still be unpredictable in the details of their occurrence, are nevertheless interpretable, and many of their distinctive features are no longer within the realm of the unknown. We now know a great deal about the dynamics involved in historical epidemiological processes, such as the rate of spread of an infectious disease and the factors underlying its incidence or virulence. Thanks to the increasing availability of historical longitudinal micro-data, we also know more about the factors modulating the individual risk during an outbreak, how sex and age patterns of mortality are modified, and how these patterns differ from other times when mortality is simply high, but for other reasons. Who were at the highest risk? Males or females? At what ages? We can now answer these questions with relative confidence.