Some years since, I began a study of the Eugenics of War, the hereditary effects of the systematic extermination by war of the bold and strong among the yeomanry of the nations of Europe. The first results of this study I set forth in two little books, "The Blood of the Nation" and "The Human Harvest." I soon found it necessary to consider also the "Euthenics" of War, the non-hereditary effects of the financial impoverishment of the rank and file of the people by the cost of war and war armament. This little book is a preliminary survey of the elements involved in this subject. There is a Persian proverb, "He who knows will never tell." In this lies my justification for venturing into a field in which first-hand knowledge is largely out of my reach. I am indebted to Mr. E. Alexander Powell for the phrase, "The Unseen Empire." I am also under obligations to my colleagues, Professors Edward Benjamin Krehbiel, Alvin Saunders Johnson, Payson Jackson Treat and Albert Leon Guerard for suggestions of various kinds. I am also indebted to Mr. Arthur W. Allen of the World Peace Foundation for the tables in the appendix, showing the record of debt and expenditure.