The great war has entered into history. The restraints, direct and indirect, which it imposed being gone with it, we return to sounder tests of what should be public knowledge—uncomfortable truths may be told, secret places explored. At the same time, the first squall of controversy in France over the opening of the land campaign in the West has subsided; this lull is the student’s opportunity. No complete history of the events culminating in the victory of the Marne is yet possible, or soon to be expected. On the German side, evidence is scanty and of low value; on that of the Allies, there is yet a preliminary work of sifting and measuring to undertake ere definitive judgments can be set down. Any narrative conceived in a scientific, not an apologetic or romantic, spirit may claim to further this end.

The difficulty lies less in following the actual movements of that great encounter—the most important of which, and their part in the result, can now be traced pretty accurately—than in estimating the factors that produced and moulded it. Yet, if we are right in holding the battle of the Marne to be essentially the completion of a chapter, the resultant of certain designs and certain misadventures, a vast strategical reversal and correction, such an estimate is necessary to the subject. How did the two chief antagonists envisage the process of modern warfare? Why was the action which was to close the first phase of the war, and largely to shape its after-course, fought not near the northern or eastern frontiers, but between Paris and Verdun? Why and how were the original plans of campaign modified to reach this result? What conditions of victory existed on the Marne that had been lacking on the Sambre? In a word, the key to the meaning of the battle must be sought in the character of the forces in play, their comparative numbers, organisation, and training, armament and equipment, leadership and inspiration.

No sooner is such an inquiry opened than a number of derivative problems appear. Where exactly lay the German superiority of force at the outset, and why was it not maintained? Was the first French concentration justifiable? If not, was it promptly and soundly changed? Could the northern frontier have been defended? Was Lanrezac responsible for Charleroi, and, if so, why not Castelnau for Morhange? Was the German plan of envelopment exaggerated? Could the British have done more at Mons, and were they slow and timorous when the hour arrived to turn about? Was Paris ever in danger? And, coming to the battle itself, how was it decided? What parts did Gallieni, Von Kluck, Sir John French, and Foch play? Was Joffre really master of the field? It may be too soon to answer fully such questions as these; it is too late to evade them.

Outside the mass of official and semi-official bulletins, dispatches, and explanations, much of it now best left to oblivion, a considerable literature has accumulated in France, including personal narratives by combatants of all arms, and critical essays from points of view the most diverse. With the rather cruel sincerity of the French intelligence, the whole military preparation of the Republic has been challenged; and, in the consequent discussion, many important facts have come to light. Thus, we have the texts of the most decisive orders, and many details of the dispositions of troops. We have Marshal Von BÜlow’s valuable diary of field movements, and the critical reflections of distinguished officers like Lt.-Col. de Thomasson, Generals Malleterre, Berthaut, Verraux, Percin, Canonge, Bonnal, Palat, Cherfils, and Col. Feyler. Fragmentary statements by General Joffre himself, by Generals Foch, Lanrezac, and Maunoury, the Ministers of War, MM. Messimy and Millerand, by Generals von Freytag-Loringhoven, Von Kluck, and other German officers and men, give useful indications. We are also indebted to the more systematic works of MM. Hanotaux, Reinach, Engerand, and Babin; and, with regard to the British Force, the volumes of Marshal French and Major-General Maurice are important. These and other sources are cited in the pages of “Notes and References” at the end of the volume, in which some questions of detail, especially relating to the preparation of the battle, are discussed.

Having been privileged to watch the war in France from beginning to end, and to live with the French armies (as Correspondent attached to General Headquarters) for more than two years, the writer has also had exceptional opportunities of studying the terrain, and of discussing the drama as a whole and in detail with officers and men from the highest to the most humble. To name all those from whom he has received aid would be impossible; to name any might seem to associate them with conclusions for which he is solely responsible; but he may record his deep gratitude to the French Government, the Headquarters Staff, and the various Army Staffs, for the rare experience of which this volume is unworthy fruit.

February 1920.

German units are throughout numbered in Roman capitals (“the XX Corps”), Allied in ordinary figures (“the 20th Corps”).

The small figures in the text refer to “Notes and References” at the end of the volume.