The jagged decline of great power war conceals two trends that until recently went in opposite directions. For 450 years, wars involving a great power became shorter and less frequent. But as their armies became better manned, trained, and armed, the wars that did take place became more lethal, culminating in the brief but stunningly destructive world wars.

Steven Pinker, Enlightenment now: the case for reason, science, humanism, and progress, New York, 2018, p. 157