It is the tragedy of history that man cannot free himself from war. Indeed, far more than by the development of art or literature or trade or political institutions, the history of man has been determined by the wars he has fought. Time and again, advanced and cultured societies have been laid low by more primitive and virile enemies with superior military institutions and a stronger will to fight. The end of the Cold War, the rise of globalization, the spread of democracy, and the advent of a new millennium raised hopes that mankind might move beyond the catastrophic wars that shaped the 20th century. Those hopes were dashed by Somalia and Rwanda and Bosnia, by the Sudan and the Congo and Kosovo, by Chechnya and Afghanistan and Iraq. Understanding war, not as we would like it but as it is, remains the central question of international politics. And for the most primal of reasons:War isn't going anywhere. Political and military leaders are notoriously averse to theory, but if there is a theorist about war who matters, it remains Carl von Clausewitz, whose Vom Kriege (On War) has shaped Western views about war since the middle of the 19th century. While it goes too far to say, as John Keegan has, that Clausewitz influenced every statesman and soldier interested in war for the past 100 years most never actually read or grasped him Clausewitz endures, not because he is universally understood or accepted but because he is so often right about first principles. Much of what he wrote about the conduct of war in the pre-industrial era, about marches and magazines and the war of posts, fits best with his own time. But his insights about the nature of war itself remain uniquely and enduringly prescient. Clausewitz described war as nothing more than a duel on a larger scale ... an act of force to compel the enemy to do our will.