As the United Kingdom begins another national security review, it needs a realistic conception of the sorts of wars it is prepared to fight. Public perceptions are shaped by the memory of the two world wars, and they are often reinforced by political rhetoric that emphasises that message. But over the last two hundred years, 86 per cent of deaths in inter-state wars have been caused by only 10 per cent of those wars. Most conflicts, including all those fought by Britain since 1945, have been limited in duration or, if protracted, in intensity.
So Carl von Clausewitz was wrong. A veteran of the Revolutionary and Napoleonic Wars, Clausewitz concluded that war’s nature was to escalate: conflict is bloody and violent, and killing makes compromise more difficult. However, he also recognised that in practice many wars had proved limited, an oddity he attributed to two factors.
The first was the product of the inherent constraints on its conduct imposed by weather, geography, failures of communication and inadequate intelligence. The second was external. War could be consciously contained by the pursuit of limited objectives. Such wars ended, not with the imposition of a dictated peace after a war of annihilation, but in negotiation between the two sides. Most thinking about limited war from Clausewitz’s day to our own has focused on the idea that policy best limits wars.
After 1815, the belief that the French Revolution of 1789 had precipitated a 20-year conflict caused conservatively minded governments to exercise restraint in war’s conduct. Europe, then as now, fancied itself a continent largely freed of the incubus of major war. One of the principal reasons why the First World War was both intense and protracted was that both sides were ready to overthrow this assumption. By turning their own fear of revolution into a weapon for use against their enemies, they unleashed effects that could not be contained: Britain did so with continuing consequences in the Middle East, and Germany did so in Russia. In January 1918, the American president, Woodrow Wilson, responded with the principle of national self-determination. Although he was trying to defuse the appeal of the Russian revolution to the war-weary peoples of Europe, in practice he stoked further conflict which ran on until 1923. Policy and politics could expand war as well as contain it.
After 1945 the arguments for limiting war were underpinned by new technologies and particularly by the mutual restraint induced by the possession of nuclear weapons. Policy continued to give expression to these ideas through deterrence, through what were specifically designed to be limited wars in Korea and Vietnam, and through the superpowers’ pursuit of “proxy wars”, particularly in sub-Saharan Africa and Latin America. Recent practice therefore supported the idea that fighting for limited objectives can give utility to war. Since the 9/11 attacks, the West has fought limited wars on the assumption that they can conform to this model, but Iraq, Afghanistan and Libya suggest that they do not: those wars have not delivered demonstrable results, becoming protracted, indecisive at best, and outright failures at worst. This has been so for three principal reasons.
First, the Cold War led Nato states to be selective in their reading of Clausewitz. They saw policy as only limiting war, when Clausewitz knew from his own experience of the French Revolution that policy can expand war, and that democracy itself can drive that expansion. Britain and the United States, with their joint veneration of Winston Churchill’s war leadership in 1940-41, have even less excuse than most for neglecting that point. Given war’s tendency to escalate, the policy that mobilises the whole nation can exploit war’s nature and so more effectively unite the conflict with its political objective.
Second, since 9/11 statesmen in both countries have implicitly recognised this point by invoking major wars of high intensity when addressing their electorates, as George W. Bush and Tony Blair did in the run-up to the Iraq war, although in reality they and their successors fought limited wars of low intensity. Some of their critics would argue that this was why they failed: they did not commit the resources and effort required to achieve military victory. They also failed to remember that limited wars had to end in negotiation, even with terrorists.
Third, and as a result, Western powers have become accustomed to waging limited wars, while using the vocabulary of major war. Most of them, including Britain, no longer possess the capacity to fight major wars without the US, and Ben Wallace, the defence secretary, has now warned that is exactly the situation for which the United Kingdom must prepare. The West’s wars have been constrained by the resources allotted them. It has limited defence spending’s fiscal impact on populations at home, while its armed forces in the field have been constrained by domestic political norms and by the laws of armed conflict. As a result, wars have been waged indecisively, and what were intended in 2002-3 to be short wars of high intensity have become long wars of low intensity.
The prime cause of that imbalance has been that, while the US and its allies have wanted to fight a limited war, and thus did not use the full range of capabilities at their disposal, their enemies have been engaged in unlimited wars, while lacking the resources to bring them to a conclusion. The post-9/11 wars have been characterised by the lack of equivalence between the warring parties: one side limits them by design, and the other by necessity. Most conspicuously the laws of armed conflict apply to one side only. Even in the Second World War, the Hague conventions and their successors conditioned the behaviour of both sides; today one side (rightly and necessarily) takes prisoners and respects non-combatant immunity, while the other does not.
So-called wars of choice (today’s alternative to wars of necessity or existential conflict) are optional because they are expeditionary, fought at a distance, and with minimal danger, despite the fear of domestic terrorism, to the homelands of those who undertake them. For Western powers the limitation in today’s war is geographical. For Britain, this should look familiar. As an island, dependent above all on its navy in the event of major war, Britain could opt to take a limited part in a major continental war. Its sensible strategy, according to Julian Corbett before 1914 and Basil Liddell Hart before 1939, was to wage a long war of low intensity, not a major war of high intensity. It should conduct economic warfare, while sustaining its own global trade to supply its continental allies.
The fact that it fought both world wars very differently, twice creating a mass army for use in Europe, shows the limitations of maritime power when used in isolation in the context of major war. But that experience should not blind Britain to the importance of maritime power in more limited forms of war. Today’s debate should not be about aircraft carriers specifically, but about naval strategy more generally. The sea, more than the land, creates opportunities for reciprocal restraint, precisely because, as Corbett observed, man lives on the land, not upon the sea. Naval power remains overwhelmingly a state asset, for all the sea’s use by pirates and drug-runners. Tensions and clashes at sea are, by their nature, limited in their effects. Many levels of “competition” (to use the Ministry of Defence’s current descriptor of choice) below the level of open war are available for use by navies, from the imposition of sanctions to the advanced deployment of assets. The steps in any escalation can therefore be more clearly signalled and demarcated, and their meanings are less likely to be muddled or confused by third parties. There is also a cultural point: land power temperamentally opts for short wars of high intensity, while sea power has become conditioned to long wars of low intensity.
Finally, and possibly most importantly, sea power suits alliances. National interests on land are regional in the first instance, as the Nato leaders’ meeting in Watford demonstrated: Turkey prioritised its Syrian border, France southern Europe and migration from North Africa, the Baltic states Russia, and the United States the rise of China. These geopolitical differences also have maritime dimensions, but here the effects of distance or proximity are more diffuse, and in some ways defused. The claim of Pax Americana to protect the “global commons” resonates with greater authority than do US interventions as “the global policeman”. The sea, with its international standards in navigation and mercantile safety, and the reciprocity in their observance, underpins military power with a wider economic and commercial dimension. It is perhaps no surprise that the European Union (EU) has been an effective actor in countering piracy (in the Indian Ocean), or that Britain’s first instinct was to turn to its European allies, and not to the US, when addressing tensions with Iran in the Straits of Hormuz in 2018.
Since 1945, Western states have consistently favoured limited forms of war in terms of capability and intensity, and whether defined politically or geographically. In some respects, however, those limitations have prevented them from waging war effectively. In particular, limited war has created a divergence between war in practice and the more open-ended aspirations of policy statements. Donald Trump’s presidency reflects this tension. The policies on which he was elected rejected the long wars of low intensity in which the US was then engaged. In office, his rhetoric has threatened major war, but his actions—even against Iran in January 2020—have avoided all forms of general conflict. As Britain withdraws from the EU and plans another national security review, it must prioritise how, where and with whom it is likely to fight. This will be difficult when its capabilities depend ever-more closely on a power whose worries lie more in the Pacific than in the Atlantic, and whose relationship with Nato is transactional, not unconditional.
The combination of Brexit and the uncertain direction of US foreign policy requires Britain to clarify choices whose implications it has glossed over for too long. Recognising the realities of limited war is vital in establishing the strategic coherence which should be the first step in any review of national security.