How Peace Ends

Why do some peace settlements last and others fail? I analyze a game-theoretic model in which a war-winning coalition's ability to deter revisionist challenges depends on weathering shifts in intra-coalition power. Bargains within and across formerly warring sides are linked, such that the failure of one presages failure of the other, and the success of one presages success of the other. Under some conditions, individual incentives for preventive conflict interact to make the settlement more, rather than less, stable. But when one member of a war-winning coalition will grow substantially stronger, peace settlements can fail because (a) coalition partners fight over shares of the postwar pie or (b) former enemies attack to exploit failures of collective deterrence. An empirical analysis of peace settlements following coalition victories since 1816 shows, consistent with the latter prediction, that the risk of war between former enemies increases in the predicted risk of war between coalition partners that hope to deter them.