"Sharp wars are brief," Francis Lieber wrote in his code, encapsulating in four short words an entire ethical worldview that would ground his work on the law of war. Lieber believed that the over-regulation of war was dangerous because it risked prolonging the conflict, which in the long run was damaging to human affairs. For Lieber, as for Kant, the goal of war was to return to a state of peace, and anything that made the "return to peace more difficult" should be discouraged or outlawed. On the other hand, though, "sharp wars are brief" is a horrible argument and subject to abuse. It can be used to defeat almost any regulation of war, whether sensible or not.In this paper I wish to make three key claims. First, Lieber's conception of necessity stems directly from his philosophical claim that sharp wars are brief. Second, the Lieberian conception of necessity is not a relic of the historical past. Rather, it represents the basic structure of today's law of war. If one wants to know why today's law of war does so little to value the lives of combatants — while protecting civilians — one need look no further than the Lieber Code and its argument that sharp wars are brief. Finally, the third section of this chapter will critically evaluate Lieber's assertion and ask why the laws of war assign so little value to the lives of combatants. The paper will conclude with a very limited normative defense of this state of affairs, but the existing law will not emerge unscathed. I will suggest that even if Lieber is correct that sharp wars are brief, this insight still leaves open the question of their optimal level of sharpness, which we arguably have not yet reached. Reform is still permitted and indeed required.