The Preventive War that Never Happened: Britain,France, and the Rise of Germany in the 1930s

The theory of “preventive war” states that, under certain conditions, states respond to rising adversaries with military force in an attempt to forestall an adverse shift in the balance of power. British and French passivity in response to the rapid rise of Germany in the 1930s would appear to constitute one of the leading empirical anomalies in the theory, one the theory's proponents must explain. After clarifying the meaning of the preventive motivation for war and specifying the conditions under which it should be the strongest, we examine French and British behavior in the crises over the Rhineland in 1936 and Sudeten Czechoslovakia in 1938 through an intensive study of government documents and private papers. We argue that French political leaders, anticipating a continuing adverse shift in relative power, wanted to confront Hitler, but only with British support, which was not forthcoming. British leaders believed, even by 1936, that the balance of power had already shifted in Germany's favor, but that German ascendancy was only temporary and that British rearmament would redress the balance of power in a few years. We contrast our argument with alternative interpretations based on domestic political pressures and ideologically driven beliefs and interests.