The EU remains by design and aspiration a project of peace. Yet a deteriorating global security environment requires policymakers supervisors and private-sector actors to contemplate an unprecedented question: how would the European System of Financial Supervision function (ESFS) – and how might it have to evolve – were the EU or NATO drawn into armed conflict? This article analyses from a legal and strategic perspective the extraordinary measures that could be deployed to safeguard the Single Market for financial services in wartime. After setting out the relevant treaty bases the discussion examines: (i) emergency legislation and supervisory override of business-as-usual (SOBAU); (ii) likely pathways towards further institutional centralisation; (iii) the special role of emergency money – ranging from historic Notgeld to a future Digital Euro with offline functionality; and (iv) the preparedness agenda for financial institutions. The contribution concludes that pre-emptive legal clarity ...