Such ideas and feelings are not always all that is required (we shall only instance here the once famous dictator Wedel, at Züllichau, in 1759); but the worst of all is that they are seldom durable, and they forsake the general at the last moment if great complex cases branching out into a thousand relations bear heavily upon him.
We therefore believe that a direct defence of a river with large bodies of troops, under favourable conditions, can lead to successful results if we content ourselves with a moderate negative: but this does not hold good in the case of smaller masses. Although 60,000 men on a certain length of river could prevent an army of 100,000 or more from passing, a corps of 10,000 on the same length would not be able to oppose the passage of a corps of 10,000 men, indeed, probably, not of one half that strength if such a body chose to run the risk of placing itself on the same side of the river with an enemy so much superior in numbers. The case is clear, as the means of passing do not alter.
We have as yet said little about feints or demonstrations of crossing, as they do not essentially come into consideration in the direct defence of a river, for partly such defence is not a question of concentration of the army at one point, but each corps has the defence of a portion of the river distinctly allotted to it; partly such simulated intentions of crossing are also very difficult under the circumstances we have supposed. If, for instance, the means of crossing in themselves are already limited, that is, not in such abundance as the assailant must desire to ensure the success of his undertaking, he will then hardly be able or willing to apply a large share to a mere demonstration: at all events the mass of troops to be passed over at the true point of crossing must be so much the less, and the defender gains again in time what through uncertainty he may have lost.