Pre-emptive War as a Manifestation of Hegemonic Power: Rome, Britain, and the United States


Dr Paul Robinson

Acting Director

Institute of Applied Ethics

University of Hull, England





Just as the United States of America dominates the world today as a ‘hegemonic power’, so once did Britain and Rome.  It is the purpose of this paper to compare the use by contemporary America, nineteenth century Britain and Ancient Rome of the strategy of pre-emptive war.  In so doing it will suggest that the doctrine of pre-emptive war is one promoted by those with great power to justify the aggressive use of force in pursuit of their own hegemonic interests.  I will show that both Rome and Britain regularly fought what they claimed were ‘pre-emptive wars of self-defence’, justified by exaggerated fear of largely non-existent threats.  Romans and Britons were willing to fight over these flimsy pretexts because their power was sufficiently strong to enable them to do so at relatively little cost to themselves.  In short, they made war because they could.  Other weaker powers did not have the luxury of engaging in ‘pre-emption’ in the same way, and from the perspective of those attacked in these wars they could not be described as anything other than ‘aggression’.  One can now observe a similar pattern in the wars of the United States of America, most especially the 2003 invasion of Iraq.  I will conclude that the purpose of the doctrine of pre-emption, today as in the past, appears to be to provide a means by which hegemonic powers can re-define aggression as self-defence.   As such it is not a doctrine which one can expect anybody other than those with hegemonic power to accept.

It should be stressed that the form of ‘pre-emptive war’ in question does not refer to military action taken against actually existing threats which pose an imminent danger to national security.  Rather, the subject of the paper is military action undertaken against threats which are more remote, and may not even have yet manifested themselves.  As we shall see, Romans, Britons and Americans have all fought wars of this second kind.


Ancient Rome

Hegemonic powers do not feel secure in their hegemony.  According to one recent history:

The Romans seem to have perceived foreign relations as a competition for honor and status between Rome and barbarian peoples; by proving its superior force through war and conquest, Rome extracts deference and reverence from other nations, who then remain submissive, refraining from revolt or attack.  It is in this way that the empire is supposed to maintain security.  Conversely, signs of weakness on Rome’s part, such as a show of deference to a foreign people, or failure to avenge a defeat in war or to punish a revolt with sufficient ferocity, are considered invitations to disasters.  For these reasons the Romans sometimes seem to react very aggressively to apparently minor breaches of treaty, to exaggerate the threat posed by rivals, and to respond to crises with conquest or even attempted genocide while insisting that their concerns are for their own security.[1]


            We observe in this quotation a pattern which will reappear in both the British Empire and twenty-first century America.  Great powers often have to secure vast areas with very small military forces (a mere 300,000 at the peak of the Roman Empire, even fewer at the peak of the British Empire).  Security comes to depend on portraying an impression of strength. This entails forceful responses to any perceived defiance.  The watchful hegemons soon display a tendency to see threats and insults where none exist, and then to lash out at those who are perceived as challengers.  In short, they manifest a form of defensive aggressiveness.

            It is noticeable that histories of the expansion of both the Roman and British empires often promote the theory that these empires were built for purely defensive purposes.  In the case of Rome, this theory claims that ‘Roman conquest did not flow from a master plan of world domination.  It was foisted upon Rome by circumstances’.[2]  There was, says E. Badian, a ‘traditional policy of avoiding major aggressive wars and administrative commitments’.[3]  When Rome did annex land, it did so solely because the persistently aggressive behaviour of the owners had left Rome with little choice for its own safety.

The problem with this theory is that there are too many examples of outright aggression to make it plausible.  One such was Julius Caesar’s attack on the German tribes led by the chieftain Ariovistus.  These had settled in Gaul, and Caesar justified his attack on them by claiming that:

If the Germans formed a habit of crossing the Rhine and entering Gaul in large numbers, he saw how dangerous it would be for the Romans.  If those fierce barbarians occupied the whole of Gaul, the temptation would be too strong: they would cross the frontier into the Province ... and march on Italy ... This danger, he considered, must be provided against immediately.  Moreover, Ariovistus personally had behaved with quite intolerable arrogance and pride’.[4]


We see in Caesar’s quote a clear exposition of the theory of pre-emptive war.  An act of unprovoked aggression (for such it was) was justified by a succession of ‘ifs’, designed to conjure up a terrible threat which had to be dealt with ‘immediately’, but which never in fact existed.  Similar pre-emptive logic was used by Cato the Elder to justify the Third Punic War, which destroyed Carthage, by then a shadow of its former might (Cato said that the war was necessary to forestall growing Carthaginian power – some other Romans, though, felt that Rome’s actions were unjust, as Carthage no longer posed any threat).

            What is interesting in these cases is that Caesar and Cato felt it necessary to produce a pretext for aggression.  It was not acceptable to wage war for any reason.  Under the Republic at least, it was necessary to persuade Senate and people to agree to war.  If the people felt that there was not a just cause, and that the war was not compatible with the honour of Rome, then war would not happen.

The only just causes in Roman eyes were defence of oneself or one’s allies, and response to provocation.  The emphasis on self-defence was especially strong in the late Republic, when ‘at least a handful of senators probably felt a serious philosophical aversion to wars that were not genuinely defensive’,[5] Cato the Younger being the most notable example.  As Susan Mattern says, the idea was ‘well atttested’ that ‘wars of conquest ought not to be simply plundering missions, or occasions for self-aggrandizement’, though plunder and self-aggrandizement were permitted as an incidental by-product of ‘just’ wars.[6]

The origins of this attitude lie in what was known as the ‘fetial law’, which laid down certain criteria for a just war.[7]  By the late Republic the fetial law had fallen into disuse.  Nonetheless, despite some argument to the contrary,[8] it was not irrelevant.  For even if it did not act to stop Rome fighting ‘unjust’ wars, it did influence the way they framed the justice of their actions. ‘Its effect was that Roman senators were conditioned from their earliest history to the notion of justifying a war in terms of the other party’s wrong-doing’.[9]

            This had important practical consequences.  An unjust war brought dishonour upon Rome, and so senators felt justified in punishing those who waged one. For instance, when Lucius Hortensius stormed and sacked the Greek city of Abdera, the Senate determined that Hortensius had waged an unjust war. It then freed all those whom he had enslaved, and restored to Abdera its freedom and independence.[10] 

It is true that in this and other cases, factors other than justice also motivated the Senate.  Romans were extremely envious of successful colleagues.[11]  The restoration of freedom to the people of Abdera may have been done from a desire to humiliate Lucius more than from a sense of justice.  These facts created an interesting dynamic.  Roman generals sought glory by fighting wars.  But they had to find a way to make their aggression appear just, in other words defensive, in order to avoid giving their domestic political enemies an opportunity to attack them.  To do so, they played on Romans’ paranoia about external threats.  Rome had at one time been occupied by the Gauls, and the army of Hannibal had appeared before its walls.  Romans were in consequence susceptible to scaremongering.  By conjuring up images of Ariovistus’s Germans marching on Rome, Caesar could easily persuade most that his ‘pre-emptive war’ was in truth an act of self-defence.    

From the point of view of the Germans, though, as of every target of Roman aggression, there was nothing defensive about Caesar’s actions.  Caesar used the overwhelming power of his state to assault a much weaker opponent on the pretext that the latter posed a potential future threat.  In truth, it was precisely the Germans’ weakness that made them such an attractive target.  Caesar attacked them not because they were dangerous, but because he knew he could defeat them and he wanted the glory which victory would bring.  This fits in with a general pattern.  As one commentator says, the Romans attacked numerous enemies, not because they feared them, but ‘because they had nothing to fear. ... Most Roman wars, if not all, were undertaken from a position of strength when Rome was secure in its military superiority’.[12]  Roman behaviour, writes William Harris, ‘can be explained convincingly without much recourse to defensive thinking.  Often the hostile or disobedient actions of other states seem to have had the effect of attracting Roman attention.  The Romans, for their part, would have found someone to march against in any case’.[13]



 Imperial Britain

One can observe a similar pattern in the expansion of the British Empire almost two thousand years later – a paranoid view of potential threats, a sensitivity to insults to national honour, and a corresponding tendency to engage in ‘pre-emptive’ wars of aggression against much weaker opponents, defeat of whom brought glory to the Empire. 

One of the oddities of the phenomenon was that the leaders of British governments in the late nineteenth century, most notably William Gladstone and Lord Salisbury, were men who had no desire to add territory to the empire.  Historians of British imperialism therefore tend to explain the great expansion of the Empire in that era in terms of pre-emptive defence.  Britain conquered much of the world in order to prevent others conquering it or to prevent others becoming so strong that one day they might be in a position to threaten British hegemony.  From the subjective position of the British, one could possibly describe this logic as ‘defensive’.  From the point of view of the natives of the conquered lands, it is hard to see how such a label applies. Furthermore, the defensive logic also happened to play very usefully into the hands of more aggressively inclined Empire builders, who wished to expand commerce and conquer land, or of ideologically-inclined dreamers who wished to spread Christianity and the benefits of Western civilization.

Two examples illustrate the British use of the doctrine of pre-emptive war – the South African War (Boer War), 1899-1902, and the 1903 invasion of Tibet.  At the time of these wars, Britain was at the peak of its power, but countries such as Germany, France and the United States were developing advanced industrial economies and Britain’s status as number one nation was increasingly insecure.  It became ever more important, therefore, to maintain an image of power, and not to lose face in any circumstances.[14]  Sensitivity to insults to national honour increased as a result.   
            Where one is afraid of not appearing strong in the face of threats, one tends to assume the worst.  If one does not know whether a threat exists or one has been insulted, one must assume that it does or one has and respond accordingly.  As a result, the British, like the Romans, developed paranoid views about the nature of the threat to their Empire.  To counter the threat, some then demanded pre-emptive action.

 One such ‘threat’ was to British possessions in South Africa from the Boer republics of Transvaal and Orange Free State, which in the last two decades of the nineteenth century became extremely rich due to discoveries of gold and diamonds.  Fearing that if the Boers were left unchecked they would eventually gain sufficient power to dominate South Africa at the expense of the British, the British High Commissioner in Cape Town, Sir Alfred Milner, demanded a pre-emptive war against them.  This he achieved by deliberately provoking a dispute with the Boers concerning the status of British residents of the Boer Republics.  Eventually, the Boers, aware that the British intended to attack them, pre-empted their pre-emption by attacking first.  The Boer pre-emption, though, was of the sort that is generally recognised as legal – a strike to defend oneself against imminent attack.  The British pre-emption, though, was more distant.  There was no evidence that the Boers would have attacked the British if left to themselves.  As Prime Minister Lord Salisbury said, ‘the real point to be made good to South Africa is that we not the Dutch are Boss’.[15]   

The misfortune of the Dutch (ie the Boers) was to be weak enough to be considered beatable by the British.  Major powers such as Germany and Russia could not be pre-empted in this way, although the British did pre-empt them indirectly by occupying large parts of the world which they feared these other powers might occupy if they did not do so first.

The British were particularly concerned about the Russian threat to the prize possession of the Empire - India.  As Russia expanded through Central Asia, the British began to worry that the Russians would move through Afghanistan and Tibet and into India.  This was a bizarre fear given the logistical impossibilities of supporting a Russian army through such terrain so far from home, but many nevertheless believed that the threat was real. 

British officials in India persuaded themselves that the Russians were planning to seize control of Tibet, from where they could directly threaten India.  In a parallel with the American experience of Iraqi exiles providing false intelligence about Iraqi weapons of mass destruction, a Chinese political exile named Kang-yu Wai gave the British a copy of a supposed secret treaty between China and Russia in which the Chinese government gave the Russians exclusive rights to the economic development of Tibet.[16]  Shortly afterwards, the British invaded Tibet.

Although the British viewed themselves as acting defensively, it is very hard for an outside observer to support this opinion.  The Tibetans had not attacked, nor did they intend to attack, nor did they even have the means to attack, the British.  They had, though, refused to permit the British to trade freely in their country and had refused to accept a British envoy.  This was their real sin, and the British wished to teach them a lesson.  As Major General George Younghusband said: ‘It is never wise to stand studied impertinence, or even the semblance of it, from any Oriental. … the moment there is a sign of revolt, mutiny or treachery, of which the symptoms are a swollen head and a tendency to incivility, it is wise to hit the Oriental straight between the eyes, and to keep on hitting him thus, till he appreciate exactly what he is, and who he is’.[17]

The British, like the Romans, were at the same time both militaristic and moralistic.  Proponents of philosophies such as Muscular Christianity[18] believed in the aggressive use of force, while at the same time Britons viewed themselves as proponents of fair play who denounced the ‘bully’.[19] It is quite obvious that the British bullied both the Boers and the Tibetans, but they did not wish to think of themselves in that way.  They therefore convinced themselves that they were acting in self-defence.  Since there was no obvious threat in the immediate future, they had to invent more distant ones. 

One sees here that the role of the doctrine of pre-emption is not simply, or even primarily, to provide external justification for aggression.  Rather it is part of a process of self-deception, convincing the aggressors themselves that they are in reality acting justly.


The United States of America

 The 2003 invasion of Iraq falls into the same pattern we have observed in Rome and Britain above.   In the first place, a hegemonic power attacked a much weaker state.  In the second place, it did so on the basis of exaggerated tales of future threats.  Just as Caesar justified the attack on the Germans by a series of extremely improbable ‘ifs’ (‘If the Germans formed a habit of crossing the Rhine …  If those fierce barbarians occupied the whole of Gaul’), in 2003 the United States justified its attack on Iraq by a series of equally unjustified and improbable conditionals: if the Iraqis have weapons of mass destruction, and if they have the means to deliver them, and if they have links with terrorists, and if their leaders are irrational, and if they decide to give the weapons to the terrorists, and if they decide to use them – then they will be a terrible threat, and that is a risk we cannot take. 

            We can now say with certainty that what flimsy evidence was provided to justify this logic was false.  But the idea that Iraq posed a serious threat to the United States of America was always difficult to justify.[20]  Given this, it is hard to see perceptions of future threat as being the real cause of the decision to wage war.  This does not mean that decision makers did not believe in the threat – many clearly did, just some British leaders really believed that a Russian army might come marching through Tibet – but it seems likely that they were only able to hold this belief because they were pre-conditioned to do so by other considerations.  In other words, they believed in the threat because it provided an emotional crutch which would support the decision they had already made to start the war.

            Modern leaders need such a crutch as much as the Romans and British did, for the contemporary world still considers wars of aggression to be unjust.  The general perception, as in Rome and Britain, is that war must be fought in self-defence.  The doctrine of pre-emption appeals because it can provide the necessary justification where it would otherwise not exist. 

In 2003, just as the Romans and British felt insecure in their hegemony, Americans felt insecure after the terrorist attacks of 11 September 2001.  And just as the Romans and British decided that the route to security was hypersensitivity to real and imagined insults and threats, so too do some American decision-makers in the present era.  America, according to their logic, was attacked because it appeared weak and decadent, after it fled from Somalia and failed to deal with Saddam Hussein’s defiance over a ten-year period.  The purpose of attacking Iraq was to demonstrate strength and resolve.  As the belligerent journalist Mark Steyn wrote: ‘that’s the real reason Saddam had to go: Having cocked a snook at Washington for over a decade, he symbolised the limits of American power.  And it was necessary … to make those limits look a lot less limited’.[21]

            Iraq was also chosen because it was weak.  The Romans and British knew that their power would enable them to prevail over their opponents.  So too, the Americans in 2003 knew that they could conquer Iraq quickly and at relatively little cost.  Such a cost-free outcome was not assured with other potential opponents, such as North Korea or Iran.  In the circumstances, it is very hard to view the invasion of Iraq as in any way ‘defensive’, and from the perspective of Iraqis, who know they posed no threat to the United States, it must be impossible. 



Comparing the three case studies, one can see a recurring pattern.  Hegemonic states commit acts of aggression in order to display their power, prove their strength, and win honour for themselves.  They justify this aggression by reference to imaginary future threats, based on intelligence which is faulty at best or entirely fabricated at worst. The targets of the aggression are invariably considerably weaker than the aggressors; the ease with which they can be beaten is one of their attractions as targets.  This in turn reveals one of the characteristics of pre-emptive war.  It is a form of war fought by the strong against the weak.  This is necessarily so.  If the weak attempted to pre-empt those stronger than themselves, they would invite their own destruction (as the Boers found out).  Because of this, one can conclude that the doctrine of pre-emption lacks universality.  It is not a rule for behaviour which can apply to all. It is a manifestation of power, designed to support the power of those who already have the most, giving the powerful additional rights while depriving the weak of theirs.  It masks aggression, and provides a justification for it.  If you are the powerful, and consider your own interests paramount, then perhaps this doctrine may satisfy you.  If you are not, it is one which must surely disturb you greatly. 



[1] Susan Mattern, Rome and the Enemy: Imperial Strategy in the Principate (Berkeley: University of California Press, 2002), pp. 171-2.

[2] Jerzy Linderski, ‘Si vis pacem, para bellum: Concepts of Defensive Imperialism’, in Harris (ed.), The Imperialism of Mid-Republican Rome, p. 136.

[3] E. Badian, Roman Imperialism in the Late Republic (Ithica, NY: Cornell University Press, 1968), pp. 89-90.

[4] Caesar, The Conquest of Gaul, trans. S.A. Handford (London: Penguin, 1982), p. 45.

[5] William V. Harris, War and Imperialism in Republican Rome, 327-70 BC (Oxford: Clarendon Press, 1979), p. 174.

[6] Mattern, op. cit., p. 184.

[7] Livy, The Early History of Rome, trans. Aubrey de Selincourt (London: Penguin, 2002), pp. 69-71.

[8] See Harris, War and Imperialism, pp. 169-171.

[9] A.N. Sherwin-White, ‘Rome the Aggressor?’, The Journal of Roman Studies, vol. 70, 1980, p. 177.

[10] Paul Bentley Kern, Ancient Siege Warfare (Bloomington & Indianapolis: Indiana University Press, 1999), p. 329.

[11] John Rich, ‘Fear, Greed, and Glory: The Causes of Roman War-making in the Middle Republic’, in John Rich & Graham Shipley (eds), War and Society in the Roman World (London & New York: Routledge, 1995), p. 55.

[12] Linderski, op. cit., p. 143.

[13] Harris, op. cit., p. 200.

[14] Bernard Porter, The Lion’s Share: A Short History of British Imperialism, 1850-1983 (London: Longman, 1984), p. 116.

[15] Cited in Simon C. Smith, British Imperialism, 1750-1970 (Cambridge: Cambridge University Press, 1998), p. 90.

[16] Peter Hopkirk, Trespassers on the Roof of the World: The Race for Llhasa (Oxford: Oxford University Press, 1982), p. 160.

[17] Cited in Lawrence James, The Rise and Fall of the British Empire (London: Abacus, 1998), p. 233.

[18] For a study of muscular Christianity, see Donald E Hall, Muscular Christianity (Cambridge: Cambridge University Press, 1994);

[19] ‘Britons, above all other people’, wrote Robert Baden Powell, ‘insist on fair play.  If you see a big bully going for a small or weak boy, you stop him because it is not “fair play”.’  Robert Baden-Powell, Scouting for Boys (London: Horace Cox, 1908.  Reprinted, Oxford: Oxford University Press, 2004), p. 223.

[20] I argued this in an article published before the invasion: Paul Robinson, ‘A War for Fools and Cowards’, The Spectator, 14-21 December 2002.

[21] Mark Steyn, ‘Now it’s up to Iraqis’, The Spectator, July 2004.