How does mediation work? Uncertainty is one of the main rationalist explanations for war. When a leader faces domestic pressure and mediation involves secrecy and agenda-setting, mediation by a third party in crisis bargaining can reduce the risk of war by reducing uncertainty and locking in concessions. As a result, mediation improves the prospects for peace at the price of costlier settlements, and should talks fail, the leader and her audience are more likely to win in any ensuing war. The theory holds implications for mediation, audience costs, and democracies in showing that an enemy with no audience costs can demonstrate resolve credibly in mediation. The argument is also closely related to the delegation literature, in showing that when a principal faces external pressure, she can reduce her risk of worse outcomes by delegating to an uninformed agent who, with considerable discretion, can extract credible information from an adversary.