Introduction In the mid 19^th century, military health protection began to be informed by epidemiology. This paper examines the development of military epidemiology and its impact on military health policy.

Methods Historical material drawn from military health reports and other sources is used to illustrate long-term trends and developments.

Results The science of military epidemiology can be traced back to the Scottish Enlightenment of the 18th century. At first qualitative and descriptive, the early nineteenth century saw the development of a more quantitative and analytical approach which became a powerful tool in influencing military policy to protect and improve the poor health of the Victorian soldier, who faced disease and environmental hazards far from home. Formal annual reports on the health of the Army, which were instituted in 1859 and continue to this day, have provided a unique picture of long-term health trends in a changing population. Over time, both the nature of the disease threat and the means of health protection changed, and examples will be given of trends in disease and their impact on military operational effectiveness. The military population itself also changed as recruits became better nourished and healthier. Modern technology has updated the methodology for data collection, although not necessarily beneficially.

Conclusion Although the military population, its health problems and the methods of data collection have changed over time, the fundamental principle of basing military health protection on sound epidemiology remains constant. The lessons of the past provide evidence on which future planning can be based.