above all things, a common aim for all; but this aim must be so situated as not to paralyse the action of any of the individual parts. If we invade France from the upper and middle Rhine and Holland, with the intention of uniting at Paris, neither of the armies employed to risk anything on the advance, but to keep itself intact until the concentration is effected, that is what we call a ruinous plan. There must be necessarily a constant comparison of the state of this threefold movement causing delay, indecision, and timidity in the forward movement of each of the armies. It is better to assign to each part its mission, and only to place the point of union wherever these several activities become unity of themselves.
Therefore, when a military force advances to the attack on separate theatres of war, to each army should be assigned an object against which the force of its shock is to be directed. Here the point is that these shocks should be given from all sides simultaneously, but not that proportional advantages should result from all of them.
If the task assigned to one army is found too difficult because the enemy has made a disposition of his force different to that which was expected, if it sustains a defeat, this neither should, nor must have, any influence on the action of the others, or we should turn the probability of the general success against ourselves at the very outset. It is only the unsuccessful issue of the majority of enterprises or of the principal one, which can and must have an influence upon the others: for then it comes under the head of a plan which has miscarried.
This same rule applies to those armies and portions of them which have originally acted on the defensive, and, owing to the successes gained, have assumed the offensive, unless we prefer to attach such spare forces to the principal offensive, a point which will chiefly depend on the geographical situation of the theatre of war.