2 Carl von Clausewitz and the theory of war
Introduction: theory for all seasons
Strategic history offers a catalogue of horrors of the utmost diversity, but those grisly
events are all, without exception, explicable according to a single theory of war and
strategy. The theory available to us is largely the product of the Prussian soldier Carl von
Clausewitz (17 8 0–1 8 31). Of course, one can find some individual elements characteristic
of his thinking in the writings of earlier theorists, but the total edifice of ideas that he
constructed was monumentally original. In his unfinished work On War, Clausewitz
explained the essential nature of war, how it endures through time and circumstance, even
as its character is ever changing. He emphasized the effective, logical unity between
politics and war, and he laid stress upon war’s moral dimension. Clausewitz insisted that
war has to be a duel between competing wills, that it is subject to the many frustrations
of what he termed, collectively, ‘friction’; and he insisted that war was the realm of
chance, risk and uncertainty. He is not beyond criticism, naturally, but most scholars and
soldiers agree that his great achievement was to draft a general theory of war and strategy
that was good enough to be both highly plausible and superior to the theories of all his
rivals.
Clausewitz’s writing is an essential and central element in this study of modern
strategic history, as it has to be. He explained for all time the nature of the strategic
dimension to history. His most mature work of theory, On War, provides a framework
that enables understanding of all the strategic phenomena in the lengthy period covered
by this text. On Waris not infallible, and it might well have been improved had the
author lived longer than his fifty-one years, or had he viewed technology and industry,
and perhaps sea power, with a friendlier eye. But the test of perfection is irrelevant.
A distinguished modern American strategist, Bernard Brodie, wrote of On Warthat
‘His is not simply the greatest but the only truly great book on war’ (in Clausewitz,
1976: 53).