One dominant explanation for why crises escalate to war is based on misperception. Alternative rational explanations for why crises escalate to war are examined, including commitment problems, the cost of revealing military advantages, and a desire for greater future gains. These explanations for war argue that states are likely to prefer a military to a diplomatic solution and to mobilizetheir militaries to maximize a surprise attack advantage. This type of mobilization (private) is different from mobilization by states seeking a diplomatic advantage (public) because states are trying to avoid revealing information. When one state in a crisis mobilizes privately, war is more likely because one state is committed to conflict whereas the other is not receiving signals of an impending conflict. The effect of private mobilization on war is tested using the International Crisis Behavior data. The results demonstrate that private mobilization is likely to lead to war.