The German military’s chief of staff, General Helmuth von Moltke, made these comments on the Schlieffen Plan in a memorandum from 1911:

It may be safely assumed that the next war will be a war on two fronts. Of our enemies, France is the most dangerous and can prepare the most quickly. Accounts must be settled with her very soon after deployment. Should the defeat of the French be achieved quickly and decisively, it will also be possible to make forces available against Russia.

I agree with the basic idea of opening the war with a strong offensive against France while initially remaining on the defensive with weak forces against Russia. If a quick decision is sought against France, the attack should not be directed exclusively against the strongly fortified eastern front of that country. If, as may be expected, the French army remains on the defensive behind that front, there is no chance of quickly breaking through; and even a break-through would expose the German army, or those sections which have made it, to flank attack from two sides.

If one wants to meet the enemy in  the open, the fortified frontier-line must be outflanked. This is only possible by means of an advance through Switzerland or Belgium. The first would encounter great difficulties and, because of the defence of the mountain roads, would take a long time. On the other hand a successful outflanking of the French fortifications would have the advantage of forcing the French army towards the north. An advance through Belgium would force the French back into their interior. Nevertheless it should be preferred, because there one can count on quicker progress. We can count on the somewhat inefficient Belgian forces being quickly scattered, unless the Belgian army should withdraw without a battle to Antwerp, which would then have to be sealed off.

It is important, of course, that for an advance through Belgium the right wing should be made as strong as possible. But I cannot agree that the envelopment demands the violation of Dutch neutrality in addition to Belgian. A hostile Holland at our back could have disastrous consequences for the advance of the German army to the west, particularly if England should use the violation of Belgian neutrality as a pretext for entering the war against us. A neutral Holland secures our rear, because if England declares war on us for violating Belgian neutrality she cannot herself violate Dutch neutrality. She cannot break the very law for whose sake she goes to war. Furthermore it will be very important to have in Holland a country whose neutrality allows us to have imports and supplies. She must be the windpipe that enables us to breathe.

However awkward it may be, the advance through Belgium must therefore take place without the violation of Dutch territory. This will hardly be possible unless Liège is in our hands. The fortress must therefore be taken at once. I think it possible to take it by a coup de main. Its salient forts are so unfavourably sited that they do not overlook the intervening country and cannot dominate it. I have had a reconnaissance made of all roads running through them into the centre of the town, which has no ramparts. An advance with several columns is possible without their being observed from the forts. Once our troops have entered the town I believe that the forts will not bombard it but will probably capitulate.

Everything depends on meticulous preparation and surprise. The enterprise is only possible if the attack is made at once, before the areas between the forts are fortified. It must therefore be undertaken by standing troops immediately war is declared.