This war is the largest and the weightiest historical incident which Europe has known for many centuries.  It will surely determine the future of Europe, and in particular the future of this country.  Yet the comprehension of its movements is difficult to any one not acquainted with the technical language and the special study of military history; and the reading of the telegrams day by day, even though it be accompanied by the criticisms of the military experts in the newspapers, leaves the mass of men with a most confused conception of what happened and why it happened.

Now, it is possible, by greatly simplifying maps, by further simplifying these into clear diagrams, still more by emphasizing what is essential and by deliberately omitting a crowd of details—­by showing first the framework, as it were, of any principal movement, and then completing that framework with the necessary furniture of analysed record—­to give any one a conception both of what happened and of how it happened.

It is even possible, where the writer has seen the ground over which the battles have been fought (and much of it is familiar to the author of this), so to describe such ground to the reader that he will in some sort be able to see for himself the air and the view in which the things were done:  thus more than through any other method will the things be made real to him.  The aim, therefore, of these pages, and of those that will succeed them, is to give such a general idea of the campaigns as a whole as will permit whoever has grasped it a secure comprehension of the forces at work, and of the results of those forces.  It is desired, for example, that the reader of these pages shall be able to say to himself:  “The Germanic body expected to win—­and no wonder, for it had such and such advantages in number and in equipment....  The first two battles before Warsaw failed, and I can see why.  It was because the difficulties in Russian supply were met by a contraction of the Russian line....  The 1st German Army was compelled to retreat before Paris, and I can now see why that was so:  as it turned to envelop the Allied line, a great reserve within the fortified zone of Paris threatened it, and forced it back.”

These main lines, and these only, are attempted in the present book, and in those that are to follow it in this series.

The disadvantage of such a method is, of course, that the reader must look elsewhere for details, for the notices of a particular action, and the records of particular regiments.  He must look for these to the large histories of the war, which will amply supply his curiosity in good time.  But the advantage of the method consists in that it provides, as I hope, a foundation upon which all this bewildering multitude of detailed reading can repose.

I set out, then, to give, as it were, the alphabet of the campaign, and I begin in this volume with the preliminaries to it—­that is, its great political causes, deep rooted in the past; the particular and immediate causes which led to the outbreak of war; an estimate of the forces engaged; and the inception of hostilities.