Time Is of the Essence: The Causal Effect of Duration on Support for War

It is often observed that public support for non-existential wars diminishes over time, but the micro foundations of this observation as well as its implications for states’ war-fighting capabilities are unclear. I present a modified war of attrition model in which an exogenous event can end the war and the rate of that event is unknown to players. Players’ expectation for the remaining duration of war increases and they find fighting less favorable as time passes. But, we cannot separate the effect of cost from duration using observational data. I use a survey experiment to disentangle the effect of duration on support for war from the effect of costs. The result is that duration has a negative effect on public support for war that is stronger than the effect of aggregate casualties. This has important implications for how we should fight small wars.