Author Edward Miller makes a plausible case that a major cause of us entry into WWII was women’s fashion trends. With the advent of shorter skirts in the 1920s came high demand for silk stockings. Japan was the world’s major supplier of hosiery silk. By the 1930s, hosiery silk was the single largest imported item in the US, and American women bought 60% of the world’s silk stockings. Then, in 1939, Wallace Hume Carothers at DuPont invented Nylon.

Japan had been more or less at war with China since 1931. The Japanese had little in the way of natural resources, but their military required oil and steel. The United States was the major supplier for both; it was cheaper to transport oil across the Pacific than to get it from the Middle East, and as Europe began the build up to war Middle Eastern and South American oil went there. And the only thing the Japanese could use to buy American oil and steel was gold reserves and silk, and with the replacement of silk with nylon all that Japan could use were its rapidly diminishing gold and dollar reserves.

In 1917, the US Congress had passed the Trading with The Enemy Act, intended to prevent US entities from trading with Germany and Austria-Hungary. However, international finance was very complicated, and it was possible to move money and goods from one country to another so that the end recipient was obscured – to “launder” it, to use the modern term. Thus, the TWEA had a paragraph allowing the President of the United States to block trade and freeze assets of ANY country - enemy, neutral, or allied – even if the United States was not at war.

Thus, in the 1930s FDR invoked the TWEA to financially attack Japan over its war in China gradually invoking financial restrictions – first refusing to export oil and steel scrap, and then totally freezing Japanese bank accounts in the US preventing Japan from spending dollars elsewhere (nobody except the Japanese colonies of Manchukuo, Formosa, and Korea wanted yen). The US expected to “bring Japan to its senses”; the Japanese considered it an act of war.

That’s the gist of Edward Miller’s Bankrupting the Enemy. I never realized international finance could be so complicated and interesting. There’s a lot more to it that just the silk vs. nylon narrative above; the US studied other financial levers (for example, Japan was the world’s largest importer of fertilizer) and several US agencies (Treasury, Commerce, State, and the military) competed over who was going to run the financial war. Miller includes numerous graphs and tables carefully documenting his arguments (and notes that many of the relevant papers weren’t declassified until the 1990s). He does not discuss what else the United States could have or should have done (which would probably require a whole other book and a pretty speculative one at that). It’s interesting to note that in the 1970s there were semiserious discussions about the US going to war in the Middle East and seizing oil fields – using roughly the same arguments that Japan had used in 1941 (and which got several Japanese diplomats tried and sentenced as war criminals). Not the most exciting reading but repays careful attention. ( )

Call this an anatomy of the countdown to war with Japan from the perspective of the Department of the Treasury, and why the currency freeze was such an irrevocable decision. Whether it was a wise decision depends on how inevitable you believe war with Japan was from an American perspective. While an important book for the long-time student of the Pacific War, it's not the introduction to a wider world the way Miller's "War Plan Orange" was. As for what FDR's final intention were in all this, you can just as easily argue plausible deniability as you can failure to understand the consequences from the existing record. ( )