Defence Strategy (Clausewitz)

I. General Principles For Defense
1. To keep our troops covered as long as possible. Since we are always open to attack, except
when we ourselves are attacking, we must at every instant be on the defensive and thus should
place our forces as much under cover as possible.

2. Not to bring all our troops into combat immediately. With such action all wisdom in
conducting a battle disappears. It is only with troops left at our disposal that we can turn the tide
of battle.

3. To be little or not at all concerned about the extent of our front. This in itself is unimportant,
and an extension of the front limits the depth of our formation (that is, the number of units which
are lined up one behind the other). Troops which
are kept in the rear are always available. We can use them either to renew combat at the same
point, or to carry the fight to other neighboring points. This principle is a corollary of the
previous one.

4. The enemy, while attacking one section of the front, often seeks to outflank and envelop us at
the same time. The units which are kept in the background can meet this attempt and thus
make up for the support usually derived from ob- stacles in the terrain. They are better suited for
this than if they were standing in line and extending the front. For in this case the enemy could
easily outflank them. This principle again is a closer definition of the second.

5. If we have many troops to hold in reserve, only part of them should stand directly behind the
front. The rest we should put obliquely behind.
From this position they in turn can attack the flank of the enemy columns which are seeking to
envelop us.

6. A fundamental principle is never to remain completely passive, but to attack the enemy
frontally and from the flanks, even while he is attacking us. We should, therefore, defend
ourselves on a given front merely to induce the enemy to deploy his forces in an attack on this
front. Then we in turn attack with those of our troops which we have kept back. The art of
entrenchment, as Your Royal Highness expressed so excellently at one time, shall serve the
defender not to defend himself more securely behind a rampart, but to attack the enemy more
successfully. This idea should be applied to any passive defense. Such defense is nothing more
than a means by which to attack the enemy most advantageously, in a terrain chosen in advance,
where we have drawn up our troops and have arranged things to our advantage.

7. This attack from a defensive position can take place the moment the enemy actually attacks, or
while he is still on the march. I can also, at the moment the attack is about to be delivered,
withdraw my troops, luring the enemy into unknown territory and attacking him from all sides.
The formation in depth--i.e., the formation in which only two-thirds or half or still less of the
army is drawn-up in front and the rest directly or obliquely behind and hidden, if possible--is
very suitable for all these moves. This type of formation is, therefore, of immense importance.

8. If, for example, I had two divisions, I would prefer to keep one in the rear. If I had three, I
would keep at least one in the rear, and if four probably two. If I had five, I should hold at least
two in reserve and in many cases even three, etc.

9. At those points where we remain passive we must make use of the art of fortification. This
should be done with many independent works, completely closed and with very strong profiles.
10. In our plan of battle we must set this great aim: the attack on a large enemy column and its
complete destruction. If our aim is low, while that of the enemy is high, we will naturally get the
worst of it. We are penny-wise and pound-foolish.

11. Having set a high goal in our plan of defense (the annihilation of an enemy column, etc.), we
must pursue this goal with the greatest energy and with the last ounce of our strength. In most
cases the aggressor will pursue his own aim at some other point. While we fall upon his right
wing, for example, he will try to win decisive advantages with his left. Consequently, if we
should slacken before the enemy does, if we should pursue our aim with less energy than he
does, he will gain his advantage completely, while we shall only half gain ours. He will thus
achieve preponderance of power; the victory will be his, and we shall have to give up even our
partly gained advantages. If Your Royal Highness will read with attention the history of the
battles of Ratisbon and Wagram, all this will seem true and important.
In both these battles the Emperor Napoleon attacked with his right wing and tried to hold out
with his left. The Archduke Charles did exactly the same. But, while the former acted with great
determination and energy, the latter was wavering and always stopped half-way. That is why the
advantages which Charles gained with the victorious part of his army were without consequence,
while those which Napoleon gained at the opposite end were decisive.

12. Let me sum up once more the last two principles. Their combination gives us a maxim which
should take first place among all causes of victory in the modern art of war: "Pursue one great
decisive aim with force and determination."

13. If we follow this and fail, the danger will be even greater, it is true. But to increase caution at
the expense of the final goal is no military art. It is the wrong kind of caution, which, as I have
said already in my "General Principles," is contrary to the nature of war. For great aims we must
dare great things. When we are engaged in a daring enterprise, the right caution consists in not
neglecting out of laziness, indolence, or carelessness those measures which help us to gain our
aim. Such was the case of Napoleon, who never pursued great aims in a timid or half-hearted
way out of caution. If you remember, Most Gracious Master, the few defensive battles that have ever been won, you
will find that the best of them have been conducted in the spirit of the principles voiced here. For
it is the study of the history of war which has given us these principles.
At Minden, Duke Ferdinand suddenly appeared where the enemy did not expect him and took
the offensive, while at Tannhausen he defended himself passively behind earthworks. At
Rossbach, Frederick II threw himself against the enemy at an unexpected point and an
unexpected moment.
At Liegnitz, the Austrians found the King at night in a position very different from that in which
they had seen him the previous day. He fell with his whole army upon one enemy column and
defeated it before the others could start fighting.
At Hohenlinden, Moreau had five divisions in his front line and four directly behind and on his
flanks. He outflanked the enemy and fell upon his right wing before it could attack.
At Ratisbon, Marshal Davout defended himself passively, while Napoleon attacked the fifth and
sixth army-corps with his right wing and beat them completely.
Though the Austrians were the real defenders at Wagram, they did attack the emperor on the
second day with the greater part of their forces. Therefore Napoleon can also be considered a
defender. With his right wing he attacked, outflanked and defeated the Austrian left wing. At the
same time he paid little attention to his weak left wing (consisting of a single division), which
was resting on the Danube. Yet through strong reserves (i.e., formation in depth), he prevented
the victory of the Austrian right wing from having any influence on his own victory gained on
the Rossbach. He used these reserves to retake Aderklaa.
Not all the principles mentioned earlier are clearly contained in each of these battles, but all are
examples of active defense.
The mobility of the Prussian army under Frederick II was a means towards victory on which we
can no longer count, since the other armies are at least as mobile as we are. On the other hand,
outflanking was less common at that time and formation in depth, therefore, less imperative.