While the relationship between trade and war is ambiguous, some argue that diminished trade can pose a threat to global peace by lowering both the opportunity costs of war and the cost of raising an army. This column examines the relationship between Atlantic trade and war in Europe between 1640 and 1896, a period in which intra-European conflict decreased dramatically. It finds that the growth in Atlantic trade lowered the probability of intra-European conflict by 15 percentage points.