A New Documentary Reveals the Hidden Ideological and Scientific Roots of World War I

This month marks the hundredth anniversary of the start of the First World War. Between 1914 and 1918, the conflict took 16 million lives in brutal combat yet its causes remain strangely cloudy to most of us. One historian titled his recent book about the origins of the war The Sleepwalkers, as if nations and leaders stumbled into the global catastrophe almost by accident, unmotivated by any particular philosophy or ideology.

World War II is very different: Everyone understands what that was...