To identify elements that commonly cause global conflicts, studies the Peloponnesian and Punic wars, World Wars 1 and 2, and the Cuban Missile Crisis. Despite the modern taste for social-science explanations such as irrational behavior or systemic competition (e.g., Kennedy’s belief miscalculation launched the Great War), Thucydides’ precept holds: wars commence from honor, fear, or interest. The historian of war ought to hold out hopes of statesmanship surmounting avoidable conflict: some wars are just and must be resolved, but many can be put off, sometimes through concession but more often by deterrence. There is a typology of treaties (e.g., victor’s peace, punishment without destruction, and mutual agreement that continuing costs surmount the gains) which are the starting point for defense of peace.

Peloponnesian War: The Spartans’ honor required defending its coalition and discouraging defections to Athens. Archidamus failed to stem his fractious allies, who were more like NATO than the common analogy of the Soviet bloc. Pericles sought to demonstrate Athens was a sated power, and through defensive strategy to show traditional Spartan warfare could not prevail, but lacked a credible offensive deterrent (such as encouraging slave rebellion).

World War 1: Germany undid Bismarck’s attempt to demonstrate its satisfaction through the belligerence of Kaiser Wilhelm and his cabinet. The pursuit of naval power and colonies was a point of honor (not interest) which threatened Britain’s traditional objectives to control the seas and the Low countries and well as to preserve a continental balance of power.

2d Punic War: Rome struck a poor peace, its Senate failing to ratify the first treaty and seeking a larger indemnity, both of which served to inflame Carthage. Additionally, Rome carelessly conceded vital interests, such as the security of Saguntum or defending the Ebro border.

World War 2: Versailles was not unduly harsh, but the Germans didn’t believe they’d lost, and the UK didn’t see itself as responsible for enforcement. Its economic power flagging, Britain was persuaded by traumatized, rationalist intellectuals to trust in the League of Nations. Well before Hitler’s rise, the Germans had shaken off occupation of the Rhineland, renegotiated reparations, and begun rearming (in cooperation with Soviet Russia). Subsequently, Chamberlain replaced moral disarmament with military unpreparedness as a reason for appeasement. France too, cowering behind the Maginot Line, lacked the will to defend Eastern Europe.

Cuban Missile Crisis: Geoffrey Blainey observes wars start when rivals can’t agree the allotment of power. Both sides agreed the US was stronger but Khrushchev perceived Kennedy wouldn’t act on it. The Bay of Pigs, disastrous Vienna summit, and erection of the Berlin Wall as well as Soviet premier’s skill at strategic deception and bluster shook the American president. In belatedly exposing the Soviet missile gap, Kennedy pushed his rival into a corner without intending to keep him there. Similarly, the warning against deployment was too late for prevention, too precise to explain away their discovery. Khrushchev underestimated the pressure on Kennedy to act, just as Chamberlain had been forced by opinion to confront Hitler. (The US cabinet saw Cuba as a domestic matter not a military problem, ruing that a less precise warning would have allowed the administration to eventually explain the missiles were no threat.) Kennedy contemplated trading missiles in Turkey for Cuba very early and volunteered the terms. Khrushchev accepted the concession, taking advantage of a weak player.