The late nineteenth and early twentieth centuries in Europe and America witnessed the rise of a new form of nationalism that mobilized the sexuality of its citizens to serve the political goals of the state. Driven by Darwinian evolutionary biology, Mendelian genetics, and the increasingly popular discourse of degeneration, “mainline” eugenists working in universities and foundations linked the health of the nation with the physical, mental, and moral health of its citizens.1 As Wilhelmine E. Key announced at the Second International Congress of Eugenics in 1921, “The foundations of national power are, in the last analysis, biological.”2 One consequence of this was the belief that population growth was essential to a nation’s military strength and its geopolitical infl uence in the race for empire. Equally important to what Theodore Roosevelt described as “the warfare of the cradle” was a new but corresponding concern with the quality of a nation’s population.3 The decline and fall of empires was now seen as the result of biological rather than moral decline.4