Plan of War when the Destruction of the Enemy is the Object

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In conformity with all that has been said on the subject up to the present, two fundamental principles reign throughout the whole plan of the war, and serve as a guide for everything else.

The first is: to reduce the weight of the enemy’s power into as few centres of gravity as possible, into one if it can be done; again, to confine the attack against these centres of force to as few principal undertakings as possible, to one if possible; lastly, to keep all secondary undertakings as subordinate as possible. In a word, the first principle is, to concentrate as much as possible.

The second principle runs thus -- to act as swiftly as possible; therefore, to allow of no delay or detour without sufficient reason.

The reducing the enemy’s power to one central point depends --

1 On the nature of its political connection. If it consists of armies of one power, there is generally no difficulty; if of allied armies, of which one is acting simply as an ally without any interest of its own, then the difficulty is not much greater; if of a coalition for a common object, then it depends on the cordiality of the alliance; we have already treated of this subject.

2 On the situation of the theatre of war upon which the different hostile armies make their appearance.

If the enemy’s forces are collected in one army upon one theatre of war, they constitute in reality a unity, and we need not inquire further; if they are upon one theatre of war, but in separate armies, which belong to different powers, there is no longer absolute unity; there is, however, a sufficient interdependence of parts for a decisive blow upon one part to throw down the other in the concussion. If the armies are posted in theatres of war adjoining each other, and not separated by any great natural obstacles, then there is in such case also a decided influence of the one upon the other; but if the theatres of war are wide apart, if there is neutral territory, great mountains, etc., intervening between them, then the influence is very doubtful and improbable as well; if they are on quite opposite sides of the state against which the war is made, so that operations directed against them must diverge on eccentric lines, then almost every trace of connection is at an end.
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The first consideration in the combination of a plan for a war is to determine the centres of gravity of the enemy’s power, and, if possible, to reduce them to one. The second is to unite the forces which are to be employed against the centre of force into one great action.

Here now the following grounds for dividing our forces may present themselves:

1 The original position of the military forces, therefore also the situation of the states engaged in the offensive.

If the concentration of the forces would occasion detours and loss of time, and the danger of advancing by separate lines is not too great, then the same may be justifiable on those grounds; for to effect an unnecessary concentration of forces, with great loss of time, by which the freshness and rapidity of the first blow is diminished, would be contrary to the second leading principle we have laid down. In all cases in which there is a hope of surprising the enemy in some measure, this deserves particular attention.

But the case becomes still more important if the attack is undertaken by allied states which are not situated on a line directed towards the state attacked -- not one behind the other -- but situated side by side.
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2 The attack by separate lines may offer greater results.

As we are now speaking of advancing by separate lines against one centre of force, we are, therefore, supposing an advance by converging lines. A separate advance on parallel or eccentric lines belongs to the rubric of accessory undertakings, of which we have already spoken.