This article reveals that the diplomatic and financial history of 1931 was even more turbulent than believed to date. New documents found at the Bank of England show that an intricate system of cross-deposits was set up by the Austrian Central Bank covertly to direct funds to the Creditanstalt via American and British banks – to compensate it for taking over the bankrupt Bodencreditanstalt – suggesting that the received accounts of the collapse of the Creditanstalt need to be revised. Further, documents have come to light which show that France exacerbated the 1931 run on the Austrian schilling in order to force Austria to abandon the Austro-German customs union project of that year. This article considers the relationship between the collapse of the Creditanstalt and the abandonment of the Austro-German customs union, incorporating the new evidence to provide a novel interpretation of the financial diplomacy of that year.