The paper provides a comparative history of the economic impact of the Revolutionary and Napoleonic Wars. By focusing on the relative price evidence, it is possible to show that the conflict had major economic effects around the world. Britain’s control of the seas meant that it was much less affected than other belligerent nations, such as France and the United States. The fact that this conflict had such large price effects around the world suggests a highly inter-connected international economy, but is also consistent with the hypothesis that mercantilist conflicts prevented the emergence of more pronounced commodity market integration during the eighteenth century. The war had several longer-run effects which both helped and hindered the integration of international commodity markets during the nineteenth century.