What influence do financial crises exert on states' security policies, specifically crisisstricken states' military spending, threat assessment, and war prospects? This dissertation finds that, after the start of financial crises, the national security policies of crisis-stricken governments shift towards greater assertiveness or greater caution. Whether greater assertiveness or towards greater caution is realized depends on government exposure to high finance, that is the extent to which crisis-stricken governments rely on the largest transnational financial and business interests to solve the financial crisis. Specifically, the national security policies of a crisis-stricken government will move towards greater assertiveness if the government's exposure to high finance is low, and towards greater caution if the government's exposure to high finance is high. As a result, the national security policies of a crisis-stricken government having low affinity with high finance, namely a low predisposition to include the financial and economic preferences of high finance in its policy agenda, will be inflated when the government has a low exposure to high finance and curbed when the same government has a high exposure to high finance. Differently, the national security policies of a crisis-stricken government having high affinity with high finance, namely a high predisposition to include the preferences of high finance in its policy agenda, will become extra cautious when the government has a high exposure to high finance. The theoretical foundations underlying the argument of this dissertation do not allow determining the character of the national security policies of a crisis-stricken government having a high affinity with high finance and a low exposure to high finance. Relying on archival research, process tracing, text analysis, numerical data analysis and counterfactual analysis, I demonstrate these relationships over a total of 14 instances of financial crises affecting the security policies of a total of six states- Japan, Italy, the United States, Austria-Hungary, Germany and Great Britain-in the period between 1880 and 1940.