Why do democracies sometimes fight long, politically divisive wars that end poorly? I argue that electoral accountability, induced by party competition, can sometimes promote this and other tragic outcomes. To demonstrate this, I analyze a bargaining model in which one state is conceived of as a unitary actor while the other consists of a government and an opposition that is motivated both by electoral ambition and concern for the national interest. Perhaps surprisingly, it is the opposition’s concern for the national interest that causes the most tragic outcomes, as they may choose not to advocate peace when doing so would prevent war so as to avoid undercutting the government’s bargaining position. I close with a discussion of why the United States appears to be particularly prone to such tragic outcomes, treating the Vietnam War as an illustrative example.