Uncertainty and Bluffing Are Correct Calculations

The first cause of war is not a 'miscalculation' but a correct calculation under imperfect information: when you genuinely don't know your opponent's strength and they have an incentive to bluff that they're strong to get a better deal, your optimal strategy may sometimes be to attack to find out—like calling or bluffing in poker—and even without bluffing, if both sides start with sufficiently different priors about relative strength, that inherent uncertainty alone is a risk factor for war.