This monograph on epidemics resulting from wars is designed to bring into light an aspect of international conflict that has never been adequately appreciated. An examination of the facts here presented will indicate that until comparatively recent times the most serious human cost of war has been not losses in the field, nor even the losses from disease in the armies, but the losses from epidemics disseminated among the civil populations. It was the war epidemics and their sequelae, rather than direct military losses, that accounted for the deep prostration of Germany after the Thirty Years’ War. Such epidemics were also the gravest consequence of the Napoleonic Wars. It may appear that a study of war epidemics can have only historical interest, in view of the progress of modern medical science. Plague, cholera, and typhus can be brought under control by modern methods of sanitation. One can point to the fact that in the present great war, the only serious epidemic that has been reported is the typhus fever epidemic in Serbia. When the medical history of the war comes to be written, however, it will be found that the aggregate losses from sporadic outbreaks of war epidemics have been very considerable. A war sufficiently protracted to lead to universal impoverishment and a breakdown of medical organization would be attended, as in earlier times, by the whole series of devastating war epidemics. And even in the case of less exhausting wars, the chances of widespread epidemics is far from negligible. There is much food for reflection in the author’s account of the small-pox epidemic following the Franco-German War. In 1870 the means of coping with small-pox were as nearly perfect as they are in the greater part of the world to-day. This fact did not save Europe from a widespread epidemic, entailing human losses exceeding in gravity the losses in the field. To-day, as in the past, the probabilities of increased morbidity in the civil population, not only among the belligerents, but among neutrals as well, must be entered as a highly important debit item against war. JOHN BATES CLARK, _Director_. CONTENTS PAGE INTRODUCTION 1 CHAPTER I WAR PESTILENCES 4 CHAPTER II THE TIME BEFORE THE THIRTY YEARS’ WAR 11 CHAPTER III THE THIRTY YEARS’ WAR 25 CHAPTER IV THE PERIOD BETWEEN THE PEACE OF WESTPHALIA AND THE FRENCH REVOLUTION 79