Going into book IV I expected to receive a lesson in general tactics. This is not the case. Instead what Clausewitz has in store for us is a discussion of the engagement as an extension of strategy, a sort of demonstration of applied theory. Modernists and critics would be quick to site this book when attempting to prove Clausewitz’ irrelevance to current warfare, citing ideas that may appear at first glance to be relics of earlier generations of warfare.
Clausewitz sites rough terrain and night as being two factors that can impede military operations to the point of bringing them to a halt. In the case of night operations especially, Clausewitz shows great concern, stating that only in the most extreme cases are operations at night warranted due to the lack of control that brings with it a high probability of failure (p. 273-275).
Critics will dismiss this mode of thinking obsolete. They will say that we have mitigated much of the risk with technology. We have greatly advanced command and control, and our troops have night-vision equipment and access to radar and satellite imagery. Helicopters can be used to deploy troops in even the roughest terrain.
While this argument does have some merit, Clausewitz’ arguments, if taken in context, still hold up. While we may be able to insert troops into the most hazardous areas on the planet, it is extremely difficult to do so on a long-term basis and especially in large numbers. Additionally, we have difficulty providing the supporting arms that infantry traditionally count on. Thus operations in geographically hostile environments are perhaps more possible, Clausewitz’ warning of prudence still holds true.
Where night is concerned we are definitely more flexible. The issue is technology fails, and cannot make up for 100% of the perception lost during the day. (Ever walk a patrol wearing NVGs?) So, we “march” by night certainly. We launch surprise raids and use supporting arms to hit key targets and apply pressure to the enemy, definitely. But I would argue that the battle-proper still remains an activity for the light of day.
Another issue that might be mentioned is the fact that in describing the engagement, Clausewitz in his time was dealing with an area that was likely entirely visible from a good vantage point, while battle today may span miles. While this is true, Clausewitz’ view of the engagement scales up to the distances of modern conflict. Principles such as the power of psychological force (p. 242), and the concept of assaulting through the objective (p. 263) are alive and well today.
Book four is indeed rich with concepts that can and should be applied to the modern battlefield, more perhaps than can be consumed in one pass. While the concepts were penned in accordance with war fighting in the nineteenth century they can still be applied to the modern battle.