On War

Clausewitz’s examples in On War are typically limited to the period between the mid-18th and early 19th centuries. For this reason, it is important to review the historical circumstances of his writing to put them into a broader context. The author’s role not only as a military analyst but also as an officer in the Napoleonic Wars makes these details of his autobiography relevant to the context of his book.

First, it is not surprising that Clausewitz thought that “[p]eace seldom reigns over all Europe, and never in all quarters of the world” (40). Early Modern Europe until the mid-19th century was a divided continent fraught with armed military conflict for political and religious reasons, since there was no single authority ruling over it. The devastating Thirty Years' War (1618-1648) involved sectarianism between Protestants and Catholics and a battle for dominance between the key European dynasties. According to some estimates, the death toll from combat, disease, and starvation was unprecedented for Europe.

The Treaty of Westphalia (1648)—agreements signed in Osnabrück and Münster—concluded the war and established a new balance of power that became a foundation for European relations for centuries to come. The purpose of this balance-of-power arrangement was to ensure that no single European state had the ability to dominate others, especially in the realm of international relations and their immediate security concerns. Another key feature of the Peace of Westphalia was that it functioned regardless of which ruling dynasty was in control of the given countries. Clausewitz understands this system and mentions “the balance of power in Europe” several times (385).

The Westphalian system was unable to prevent a major European war as Napoleon rose to power (1799) and attempted to subjugate much of the continent to France. However, the balance-of-power system did not disappear. When the French lost, the Congress of Vienna (1814-1815) was a series of international meetings in the wake of the war meant to bring lasting peace to Europe, led by Austrian foreign minister Klemens von Metternich. Out of the Congress of Vienna arose an informal system, the Concert of Europe, featuring major European powers. The purpose of the Concert was to maintain peace on the continent by recognizing international borders and spheres of influence, thereby fostering coexistence.

In general terms, the Concert of Europe was rooted in the Westphalian system. Some states also formed alliances. For example, Prussia, Russia, and Austria comprised the Holy Alliance of conservative monarchies. The Concert used a congressional system and periodically met to reiterate its goals. Diplomatic meetings were held at Aachen, Troppau, Verona, and St. Petersburg in the 1820s.

This arrangement was not without challenges, such as the national uprisings—the Revolutions of 1848—and the shift in the balance of power with the formation of Germany and Italy as modern nation-states in 1871. Smaller-scale wars such as those that led to the establishment of Germany—or the Crimean War when Britain, France, and the Ottomans invaded Russia—also demonstrated the fact that Europe was not completely peaceful. However, the Concert of Europe was able to avoid a major European war until 1914, and in that sense, it displayed some limited success.

These historical developments find a reflection in Clausewitz’s book. First, his examples of warfare are limited to one between states, rather than a war of “all against all,” such as revolutionary or civil wars, and foresee the rise of nation-states in Europe. Second, he considers war a natural state because this had been the case in Europe in his lifetime and in recent history. For this reason, understanding the theory of war is one of the better ways of preparing for the next conflict. Fourth, Clausewitz emphasizes the need to establish a clear, overarching political goal for armed conflicts, writing, “War is a mere continuation of policy by other means” (11). In the author’s view, war is a “real political instrument” for attaining one’s political goals when other means have been exhausted. In his lifetime, the Concert of Europe within the general Westphalian framework was the “other means” used to attain political goals without resorting to warfare.

Fifth, Clausewitz participated in major battles against Napoleon, such as the 1806 Battle of Jena, in which Prussia lost and was forced to join France. He subsequently volunteered for the Russian Army when Napoleon invaded Russia in 1812 and was one of Prussia’s chief of staff when Prussia changed sides against Napoleon in 1813-1815. This combat experience was invaluable for helping Clausewitz formulate his theories.

Finally, the technological developments brought about by the Industrial Revolution featured strongly in the Napoleonic Wars. At this time, most European countries relied on artillery in combat—one of Clausewitz’s three arms—which comprised cannons. Napoleon, for example, preferred the Gribeauval guns for their light weight, mobility, and versatility. Overall, On War displays Clausewitz’s understanding of the key political, historical, and military questions of his day.