The emphasis for Book IV is the tactical, that is for Clausewitz, “the engagement”. What separates war from other types of social activity is fighting, that is in this context organized violence in the pursuit of a political purpose. So while the emphasis is the tactical, the whole must always be considered since tactical victory is the means of strategy.
Clausewitz’s emphasis here is on the pure concept, the principle of destruction, which is the prime tactical mission. One need only remember the stated mission of the Marine Corps as learned by this writer as a volunteer in the mid 1970s, that being, “to locate, close with and destroy the enemy by fire and maneuver or to repel their assault by fire and close combat”. The means of tactics is the destruction of the enemy. The end is military victory.
So Clausewitz isn’t saying anything particularly new or insightful here. Rather he is attempting to argue against those of his contemporaries who saw maneuver as an end in itself with the intention of establishing “base lines” or seizing “key ground” which it was thought would preclude the necessity of a bloody decision, make war a thoroughly civilized affair among a closed community of princes who respected each other and saw it as their common interest in maintaining the status quo resulting in wars of low tension and little movement to borrow the terms from Book III, Chapter 18. However there was no guarantee that future wars would return to the form of the 18th Century.
Throughout this book Clausewitz keeps the principle of destruction close to this ideal type of absolute war, since it is at the tactical level where the violence actually occurs. As Antullio Echevarria has pointed out Clausewitz’s concept of the engagement parallels his pure concept of war:
1. Destruction of the enemy’s armed forces is the main aim.
2. Destruction is attained through the means of the engagement.
3. Only major engagements produce major results.
4. Results are greatest when combined into a single battle.
5. The commander is best able to control events in a major battle.
In addition to this main point I would like to point out two other important aspects of this book. As Clausewitz writes there is a dialectical relationship between tactics and strategy (Chapter 2). Success at the tactical level providing the means and basis for strategic success, but also that changes in the tactical situation affect the strategic situation. The nature of battle can change over time with “identical organizations and methods” and the presence of “great national interests” influencing the character of engagements. Thus differences in organization and methods as well as disproportionate national interests on each side would have a fundamental influence on the nature of combat. What we describe as “battle” changes over time, but not just in obviously material ways.
Also in Chapter 2 we have this, Gradually, the units engaged are burned out, and when nothing is left but cinders, they are withdrawn and others take their place. One could argue that Clausewitz is speaking in favor of the great bloodletting of the First World War in this passage, which would be essentially the view of Basil Liddell Hart who referred to Clausewitz as the “Mahdi of Mass”. This would be also committing the cardinal sin of reading On War, that is taking quotes out of context (that is rejecting the whole) to support one’s own views: in other words creating a self-serving strawman.
So, is Clausewitz guilty as Liddell Hart charges?
No. First Clausewitz assumes an interaction between tactics and strategy. Tactical combat as an end in itself, that is massive material battles waged to grind the enemy down, is a poor means to a strategic end. As Clausewitz reminds us in Chapter 3, the subject that concerns us here is strategy, not tactics. The center of gravity present would indicate the military aim and this center of gravity need not necessarily be the enemy’s army in the field. Second, if one side is on the strategic defensive it makes no sense to waste troops in retaking ground that has been lost in defensive action especially given that one is entrenched on enemy territory with significant amounts of highly defensable enemy territory to one’s rear. What caused the German Army to suffer horrific losses at the Battle of the Somme was the constant counterattacking, which was absurd from a Clausewitzian perspective. Third, as mentioned in Chapter 4, it is the pursuit, the widening of the victory’s sphere of influence to its limit (See Book VI, Ch 29), which causes the victory to take on the nature of a major victory which can mean the end of the war. This disintergration is largely moral (loss of morale the major decisive factor, and loss of moral equilibrium must not be underestimated). Once again we have the distinction between a strategy of destruction (which Clausewitz is referring to) as opposed to a strategy of attrition (Liddell Hart’s indirect approach is another name for a strategy of attrition which does not preclude bloodletting and in the long run would cost more than a successful strategy of destruction). This possibility of pursuit however is dependent on the political and material conditions present. Successful strategies of destruction are rare in history.
I would argue that the German Army in 1914-18, and in fact all the European militaries were not following Clausewitzian strategic theory. Rather they were following more the (military) culture of their times which put a high value on notions of national superiority, sacrifice (Opferbereitschaft), and attaining a decisive decision even if the military victory had been divorced from the political purpose and had become an unrealistic end in itself, in effect war became almost autonomous. This is not to say that the general theory does not provide us with a rich and useful tool of historic analysis since I think it clearly does.
The decline of strategic thought after Clausewitz was not inevitable but was conditioned by social and political conditions. Could that be the same problem today?
To close I have several minor points:
In Chapter 5, Clausewitz seemingly reverses himself from what he had stated in the previous book, that is deception becomes the fourth objective of an engagement.
In Chapter 6, Clausewitz mentions that the duration of an engagment is a strategic element and its effects can be quite different.
In Chapter 9 do we have a connection with non-linearity, in that the shape of battle is decisively determined by its preliminary dispositions? What Alan Beyerchen describes as “sensitive to initial conditions” in his Clausewitz, Nonlinearity and Unpredictability of War?