The centenary of World War I has been a significant stimulus to new research about that conflict. Like any historical era, the meaning and consequences of the war have been reinterpreted in light of our own twenty-first century concerns. The perception that in recent years the world has witnessed a ‘return to geopolitics,’ ending the relative calm of the post-Cold War period, has made the tensions that produced the Great War appear freshly relevant. It has also refocused attention on the early twentieth-century roots of present-day conflicts. In this new international environment, U.S.-China rivalry begins to look similar to Anglo-German competition in the years before 1914, and the 1916 Sykes-Picot agreement and the treaties of Brest-Litovsk (1918) and Versailles (1919) seem to contain clues about contemporary conflicts in Eastern Europe and the Middle East.