This chapter investigates how economic interests played a role in the European security culture of the nineteenth century. At the Congress of Vienna, the principle of freedom of navigation of international rivers became institutionalised in the first intergovernmental organisation of modern history: the Central Commission for the Navigation of the Rhine (CCNR). Beyond the context of territorial demarcation during peace negotiations, the monitoring of – literally – rival interests became embedded in contemporary liberal theories of free commercial navigation as a precondition for international peace and security. This was the context in which the CCNR became the institutional framework within which conflicting interests converged in a form of international institutional cooperation that is still effective today.