At the center of Clausewitz's Puzzle lies a simple insight with important ramifications: On War is the product of Clausewitz's observation not only of Napoleon's victories at Jena and Auerstedt (1806), but also of his unsuccessful Russian campaign (1812) and of his final defeat at Waterloo (1815). As Andreas Herberg-Rothe points out, Clausewitz wrote detailed accounts of each of these campaigns between 1823 and 1827, that is, at precisely the time he was writing On War. Thus, books 3 and 4 of On War are a product of Napoleon's early victories, book 6 is influenced by his campaign in Russia, and book 8 reflects the lessons of Waterloo. Having analyzed these pivotal campaigns, Clausewitz then revised book 1, chapter 1, which is, therefore, the only part of On War that can truly be considered complete.

What does this mean for our understanding of On War? According to Herberg-Rothe, it means that Clausewitz's thinking evolved considerably over time. The early Clausewitz, for example, believed that extreme military violence was the key to success on the battlefield, while the later Clausewitz first argued that it might not lead to military victory, and then that it might even lead to the destruction of one's own army. Similarly, the “Clausewitz of Jena” privileged military success over politics, while the “Clausewitz of Waterloo” viewed war as “a modification of political intercourse, a way of pursuing political interests, and carrying out political plans ‘by means of fighting’” (34).

Herberg-Rothe recognizes that this view is at odds with much of the existing literature, which casts Clausewitz as the originator of the concept of total war. He argues, quite convincingly, that this literature places too much emphasis on the early Clausewitz. Several of Clausewitz's critics, for example, point to his discussion of the “three interactions to the extreme” as evidence that he was “the precursor of the idea of total war” (39). Herberg-Rothe responds by noting that Clausewitz also identifies “three interactions leading to the limitation of war,” and that the three interactions to the extreme “simultaneously have limiting effects in warfare” (52, 66). In a similar vein, he claims that Clausewitz's view of total war changed considerably over time. To be sure, the early Clausewitz believed that he had seen total war. There was, he believed, little difference between the concept of absolute war and the reality of war as practiced by Napoleon. In the wake of the Russian campaign, however, Clausewitz realized that Napoleon's strategy could not be successful in all circumstances and, therefore, developed the concept of “friction” in order to account for the divergence between theory and reality. Then, following Waterloo, he concluded that there were two fundamentally different types of war: war limited by politics, and unrestrained war divorced from political objectives.

Book 1, chapter 1 of On War is the end result of Clausewitz's intellectual journey, argues Herberg-Rothe, and at its core is a series of contrasts. The first is contained within the claim that war is best understood as a “wondrous Trinity” composed simultaneously of “primordial violence” and “of its element of subordination, as an instrument of policy, which makes it subject to reason alone” (96). Herberg-Rothe is at pains to point out that there is a fundamental tension here: war is made up of primordial violence, which is a blind natural force, and is at the same time a subordinate instrument of politics. Further contrasts emerge from a comparison of Clausewitz's “definition” at the beginning of the chapter, which refers to violence as an instrumental means and the tendency of combat “towards the absolute and extreme,” with the Trinity, which focuses on violence as a primordial phenomenon and on the importance of “chance and probability” in combat (101). These contrasts are important, argues Herberg-Rothe, because Clausewitz conceived of war as a process that develops within them. While the precise mix might vary, “every war … is characterized by the antithesis between the instrumental rationality of force and its primordial violence, of an immanent, necessary logic of action and counteraction, and of the play of chance and probability” (117).

Another set of contrasts exists within Clausewitz's famous “formula” to the effect that war is “merely the continuation of politics by other means.” On the one hand, notes Herberg-Rothe, this formula stresses that politics has an important effect on warfare. Yet at the same time, the formula highlights the fact that war uses means other than those used in politics. And then again by stating that war is “merely” the continuation of politics, Clausewitz suggests that war is simply part of politics. In short, “there is a tension here, a tension that cannot be overcome” (140). The source of this tension, as it is for several others, is Clausewitz's observation of Napoleon's military campaigns. According to Clausewitz, argues Herberg-Rothe, Napoleon's early victories were the product of political changes in France, which implied that politics has an important effect on warfare. The Moscow campaign demonstrated that warfare has its own laws, and the French defeat at Waterloo proved that war must be understood as being part of politics.

By exposing the contrasts between the early and late Clausewitz, between the Trinity and the definition, and within the formula, Herberg-Rothe is able to criticize a multitude of Clausewitz's interpreters, critics, and admirers. Two prominent Clausewitz critics, Martin van Creveld and Sir John Keegan, for example, are faulted for focusing narrowly on the late and early Clausewitz, respectively. The fact of the matter, argues Herberg-Rothe, is that “Keegan's criticisms could be answered with reference to the later Clausewitz, while the early Clausewitz can respond to van Creveld's criticism” (6). By failing to recognize that Clausewitz's thinking developed over time, even his most influential detractors have offered little in the way of a fundamental critique. Others, such as Sir Basil Liddell Hart and several German military thinkers, have erroneously interpreted Clausewitz as an advocate of absolute war when, as we have seen, he believed that there were two fundamentally different types of war. In short, Clausewitz readers have failed to grasp the complexity and nuance of his thought and in so doing have systematically undervalued his contribution to our understanding of war.

Clausewitz scholars will, no doubt, benefit from reading this book. Herberg-Rothe has offered a new account of Clausewitz's thought and few interpreters of On War escape criticism. But for this very reason the book is unlikely to appeal to a broader audience. Few will have the in-depth knowledge of On War and the Clausewitz literature required to follow the detailed textual analysis and the various academic debates laid out in Clausewitz's Puzzle, a task made far more difficult by the often tortuous reasoning and language. Moreover, Herberg-Rothe makes no effort to draw out the implications of his research beyond claiming that Clausewitz scholars, as a group, have done a poor job understanding him. In the prologue, for example, he notes that there has been a shift away from Clausewitz towards Sun Tzu since the Gulf War (1991) and asserts that this is unwarranted. Yet he gives no reason for his judgment and does nothing to lay out Clausewitz's contribution to our understanding of war in the past two decades. Similarly, although Clausewitz's reflections about the relationship between politics and war can presumably be applied to the current conflict in Iraq, Herberg-Rothe makes no attempt to do so. In other words, all but a small handful of readers will come away from this book with the feeling that they have a lot to learn from Clausewitz without knowing what lessons they should be learning.