3. A prudent survey of chances from the British point of view ought to contemplate that, when the German advance decisively begins, it will be backed by sufficient preponderance of force, and developed on a sufficiently wide front to compel the French armies to retreat from their positions behind the Belgian frontier, even though they may hold the gaps between the fortresses on the Verdun-Belfort front. No doubt a series of great battles will have been fought with varying local fortunes, and there is always a possibility of a heavy German check. But, even if the Germans were brought to a standstill, the French would not be strong enough to advance in their turn; and in any case we ought not to count on this. The balance of probability is that by the twentieth day the French armies will have been driven from the line of the Meuse and will be falling back on Paris and the south. All plans based upon the opposite assumption ask too much of fortune.
4. This is not to exclude the plan of using four or six British divisions in these great initial operations. Such a force is a material factor of significance. Its value to the French would be out of all proportion to its numerical strength. It would encourage every French soldier and make the task of the Germans in forcing the frontier much more costly. But the question which is of most practical consequence to us is what is to happen after the frontier has been forced and the invasion of France has begun. France will not be able to end the war successfully by any action on the frontiers. She will not be strong enough to invade Germany. Her only chance is to conquer Germany in France. It is this problem which should be studied before any final decision is taken.
5. The German armies in advancing through Belgium and onwards into France will be relatively weakened by all or any of the following causes:—
By the greater losses incidental to the offensive (especially if they have tested unsuccessfully the French fortress lines);
By the greater employment of soldiers necessitated by acting on exterior lines;
By having to guard their communications through Belgium and France (especially from the sea flank);
By having to invest Paris (requiring at least 500,000 men against 100,000) and to besiege or mask other places, especially along the seaboard;
By the arrival of the British army;
By the growing pressure of Russia from the thirtieth day;
And generally by the bad strategic situation to which their right-handed advance will commit them as it becomes pronounced.