On War Summary

On War is one of the most influential works ever written about the nature, purpose and conduct of warfare. Clausewitz argues that war is not an independent activity separated from politics. Governments use military force to achieve political objectives, and the scale and character of a war should therefore be connected to the goal being pursued. He distinguishes the abstract idea of absolute war from real war, which is limited by politics, uncertainty, human weakness and practical difficulties. He also explains “friction,” meaning the countless small problems that make even simple military actions difficult. Information is incomplete, plans fail, commanders make mistakes, weather changes and soldiers experience fear. Clausewitz therefore emphasizes judgement, courage, adaptability and an understanding of the relationship between political purpose and military means.

1. War is organized violence used to compel an opponent to accept one’s will.

1. War should serve a political objective rather than becoming an aim in itself.

1. Military strategy must be designed according to the political purpose of the conflict.

1. “Friction” refers to the unexpected difficulties that separate plans from actual performance.

1. The “fog of war” describes uncertainty, incomplete information and confusion during conflict.

1. Moral forces such as courage, discipline, public support and leadership are as important as material resources.

1. The “centre of gravity” is the main source of an opponent’s power, unity or resistance.

1. Defence is generally stronger than attack because the defender can use territory, preparation and local support.

1. Victory must be judged by whether it achieves the political objective at an acceptable cost.

1. Important quotation: “War is merely the continuation of policy by other means.” It means that military action remains connected to political objectives and should not be conducted without a clear political purpose.