War is the attempt of two human groups each to impose its will upon the other by force of arms. This definition holds of the most righteous war fought in self-defence as much as it does of the most iniquitous war of mere aggression. The aggressor, for instance, proposes to take the goods of his victim without the pretence of a claim. He is attempting to impose his will upon that victim. The victim, in resisting by force of arms, is no less attempting to impose his will upon the aggressor; and if he is victorious does effectually impose that will: for it is his will to prevent the robbery.
Every war, then, arises from some conflict of wills between two human groups, each intent upon some political or civic purpose, conflicting with that of his opponent.
War and all military action is but a means to a non-military end, to be achieved and realized in peace.
Although arguable differences invariably exist as to the right or wrong of either party in any war, yet the conflicting wills of the two parties, the irreconcilable political objects which each has put before itself and the opposition between which has led to conflict,can easily be defined.
They fall into two classes:
1. The general objects at which the combatants have long been aiming.
2. The particular objects apparent just before, and actually provoking, the conflict.
In the case of the present enormous series of campaigns, which occupy the energies of nearly all Europe, the general causes can be easily defined, and that without serious fear of contradiction by the partisans of either side.
On the one hand, the Germanic peoples, especially that great majority of them now organized as the German Empire under the hegemony of Prussia, had for fully a lifetime and more been possessed of a certain conception of themselves which may be not unjustly put into the form of the following declaration. It is a declaration consonant with most that has been written from the German standpoint during more than a generation, and many of its phrases are taken directly from the principal exponents of the German idea.
The German Object:
"We the Germans are in spirit one nation. But we are a nation the unity of which has been constantly forbidden for centuries by a number of accidents. None the less that unity has always been an ideal underlying our lives. Once or twice in the remote past it has been nearly achieved, especially under the great German emperors of the Middle Ages. Whenever it has thus been nearly achieved, we Germans have easily proved ourselves the masters of other societies around us. Most unfortunately our very strength has proved our ruin time and again by leading us into adventures, particularly adventures in Italy, which took the place of our national ideal for unity and disturbed and swamped it. The reason we have been thus supreme whenever we were united or even nearly united lay in the fact, which must be patent to every observer, that our mental, moral, and physical characteristics render us superior to all rivals. The German or Teutonic race can everywhere achieve, other things being equal, more than can any other race. Witness the conquest of the Roman Empire by German tribes; the political genius, commercial success, and final colonial expansion of the English, a Teutonic people; and the peculiar strength of the German races resident within their old homes on the Rhine, the Danube, the Weser, and the Elbe, whenever they were not fatally disunited by domestic quarrel or unwise foreign ideals. It was we who revivified the declining society of Roman Gaul, and made it into the vigorous mediæval France that was ruled from the North. It was we who made and conquered the heathen Slavs threatening Europe from the East, and who civilized them so far as they could be civilized. We are, in a word, and that patently not only to ourselves but to all others, the superior and leading race of mankind; and you have but to contrast us with the unstable Celt--who has never produced a State--the corrupt and now hopelessly mongrel Mediterranean or 'Latin' stock, the barbarous and disorderly Slav, to perceive at once the truth of all we say''...
Hilaire Belloc - The General Causes of the War, Part 1 from A General Sketch of the European War (The First Phase). June 1915.