All the foregoing circumstances taken together determine the strength or weakness of the communication of an army with its base, and this result, compared with one similarly obtained with regard to the enemy’s communications, decides which of the two opponents is in a position to operate against the other’s lines of communication, or to cut off his retreat, that is, in technical language to turn him. Setting aside all considerations of moral or physical superiority, that party can only effectually accomplish this whose communications are the strongest of the two, for otherwise the enemy saves himself in the shortest mode, by a counterstroke.
Now this turning can, by reason of the double signification of these lines, have also two purposes. Either the communications may be interfered with and interrupted, that the enemy may melt away by degrees from want, and thus be compelled to retreat, or the object may be directly to cut off the retreat.
With regard to the first, we have to observe that a mere momentary interruption will seldom have any effect while armies are subsisted as they now