World War I looms large in international relations theory. The core concepts of defensive realism—the security dilemma, spiral model, and offense-defense balance—were largely inspired by this single historical case, and evidence from the war is frequently used to test explanations built on those concepts. The new historiography of World War I, however, challenges many of the long-held assumptions about the origins of the conflict. Newly available evidence strongly suggests that German leaders went to war in 1914 with eyes wide open. They provoked a war to achieve their goal of dominating the European continent, and did so aware that the coming conflict would almost certainly be long and bloody. Germany's leaders did not go to war with a bold operational blueprint for quick victory embodied in the Schlieffen Plan; they did not misjudge the nature of modern war; and they did not lose control of events on the eve of the conflict and attack out of fear that Germany's enemies would move first. In light of the new history, international relations scholars should reexamine their empirical understandings of this conflict, as well as their theoretical presuppositions about the causes of war.