Clausewitz's "On War" reveals the essence of war to people with convincing logic and vivid discussion. He believes that war belongs to the realm of social life. It is by no means an independent act, but subordinate to politics. Not only that, politics is also the mother body that breeds war. The outline of war has been vaguely formed in politics, just like the attributes of living things have been formed in the embryo. Clausewitz put forward a wise saying on the issue of the political relationship of war, that is, "war is nothing but the continuation of politics through another means." War is not only a political act, but also a real political tool, so war must obey political needs.