As a summary of the results of our considerations, we may say, that the action against a flank is most effectual—
1. In the defensive;
2. Towards the end of a campaign;
3. Above all, in a retreat into the heart of the country; and
4. In connection with a general arming of the people.
On the mode of executing this action against the communications, we have only a few words to say.
The enterprises must be conducted by skilful detachment leaders, who, at the head of small bodies, by bold marches and attacks, fall upon the enemy’s weak garrisons, convoys, and small detachments on the march here and there, encourage the national levies (landsturm), and sometimes join with them in particular undertakings. These parties must be more numerous than strong individually, and so organised that it may be possible to unite several of them for any greater undertaking without any obstacle from the vanity or caprice of any of the single leaders.
We have now to speak of the action against the enemy’s line of retreat.
Here we must keep in view, above all things, the principle with which we commenced, that forces destined to operate in rear cannot be used in front; that, therefore, the action against the rear or flanks is not an increase of force in itself; it is only to be regarded as a more powerful application (or employment) of the same; increasing the degree of success in prospect, but also increasing the degree of risk.
Every opposition offered with the sword which is not of a direct and simple nature, has a tendency to raise the result at the cost of its certainty. An operation against the enemy’s flank, whether with one compact force, or with separate bodies converging from several quarters, belongs to this category.