Kevin Blachford, Defence Studies Department, King’s College London

Are great powers guided by a distinct grand strategy or by their world view and understanding of the international sphere? Just as modern scholars debate the nature and extent of American grand strategy, historians debate the relevance of grand strategy to the Roman empire. As the following explains, Rome was capable of making strategic decisions, but a grand strategy of imperial defence is unlikely. Instead, Roman decisions were guided by a world view, or ecumene, of civilization. Ecuneme was originally a Greek term (oikouménē), meaning the inhabited world, but under the Romans it became an idea signifying civilization itself. The ecumene of Rome was more than just a strategic culture, it was a view of international order that saw Rome as the centre of the known world. 

Today, it is equally disputed whether grand strategy guides the United States, or if grand strategy is a meaningless buzzword. It is therefore worth considering if the US and its Western allies are guided by a modern liberal ecumene. After considering the example of Rome, the following argues that the post-Cold War liberal international order has seen the American pursuit of primacy in the name of the progressive spread of universalist ideals. Not only has this approach been self-defeating, through undermining the liberal values it is meant to protect, but it appears to be closer to a strategy informed by a liberal ecumene, rather than a realistic strategy of national interest. 

Edward Luttwak’s seminal book, the Grand Strategy of the Roman Empire (1976), was a ground-breaking work for the study of grand strategy and for the study of Rome’s imperial frontiers. In taking a military strategist’s view to ancient Roman history, Luttwak’s thesis opened new ground for strategic studies but also provoked numerous heated debates for historians of the Roman empire. The claim made by Luttwak that the Romans not only thought in terms of a grand strategy, but that Rome even had the state capacity to organise such a strategy, launched numerous rebuttals and counter arguments which re-invigorated the study of Roman frontiers and Roman military history. Few scholars have had such a large impact across disciplines and no doubt some disgruntled historians felt Luttwak, as an outsider to the study of classical history, was imposing on their turf. Historians such as Benjamin Isaac pushed back against Luttwak to suggest that the Roman frontier was not a frontier at all, and that Rome was incapable of thinking in the manner of modern ideas about national security. To dismiss Luttwak’s claims entirely is to fall into the trap, though, of primitivizing Roman decision making as if there was no planning at all, but decades of research now leave many of Luttwak’s key claims open to contestation.

Luttwak’s core argument was that Roman grand strategy could be found in three imperial systems which evolved across the first to the third century AD. The first system from the Julio-Claudian dynasty rested on the management of client states with strategically mobile legionary forces that could also act as a thin perimeter for the imperial borders. The second system from Emperor Vespasian to Marcus Aurelius rested on a preclusive frontier defence with a regional deployment of forces. The final system of the third century was one of defence in depth in which the Roman armies were adapted to face the mobile threat of barbarian invasions as nomadic groups increasingly threatened control of the Rhine and the Danube frontier. Luttwak was certainly right to acknowledge that all Roman emperors were concerned in some way about the frontier. The Romans were also capable of thinking strategically, such as spreading legions out across the frontier, in order to avoid placing too great a burden on the resources of one area. The Roman military was also able to adapt the frontier to local conditions and capable of building significant forts and defensive works. Emperors such as Hadrian, Diocletian and Constantine all launched attempts to reform the frontiers with the development of new roads and the shoring up of imperial defences. 

The claim of Luttwak for an overarching Roman grand strategy, however, fails to appreciate the Roman understanding of the world they inhabited and their view of the international sphere. Measured against modern maps, Rome’s frontiers pass through twenty countries across three continents and covers nearly seven thousand miles. Luttwak’s attempt to consolidate our understanding of Rome’s management of these frontiers deserves merit, but he is creating an ahistorical argument which neglects the uniqueness of each frontier and misunderstands the reality of Roman strategic thinking. The Roman imperial borders consisted of key areas such as Hadrian’s wall, the Rhine frontier and the buffer zone of the Euphrates with rival Persia. Each frontier was adapted to local conditions, but it is not entirely clear that the Romans considered the frontier as a hard defensive line. The Romans simply lacked a modern cartographic understanding of territory. The Roman understanding of terrain was ‘odological’ in nature. This means that the Romans thought in linear terms following mountain ranges, rivers, or simply listing locations in the style of an itinerary. Cities or towns were listed as stopping points on a march rather than a visualised map of an area. The lack of maps or even a word for “map” in Latin explains the problems faced by Julius Caesar during his famous crossing of the Rubicon where he quickly lost his way in the dark and needed a local guide. Modern understandings of nation states with hard territorial boundaries are only possible because of the development of cartography. The Romans simply did not think of territory in this manner. In a pre-modern environment, the Romans sought to conquer kings not kingdoms and people not territory. 

            Because the Romans did not think in modern terms of territory it is also unclear if the Roman frontier was actually conceived of as any kind of defensive line marking the limits of imperial rule. The outermost forts of the Roman empire could just have likely been seen as staging posts or jumping off points for further conquest and to quell tribes beyond the borders. The ecuneme of Rome was a self-image or understanding of the world in which Rome existed as the sole hegemon with the right to impose Roman rule over others. Roman ideology could be summed up by the Roman historian Livy (1.16) who argued ‘no human force could resist Roman might’. The Roman ecuneme was universal in nature and understood Roman rule as stretching from ‘sunrise to sunset’, according to Philo of Alexandria (Leg 49). It is this world view of expansion and universality which allowed the Roman Emperor Augustus to even make claims of imperium over Germania despite Roman legions not actually holding the territory at the time. The ecuneme of Rome was a guiding vision which structured Roman expansion and its foreign relations. It was an ideology of empire without end which justified dominion over other peoples and accepted no equal to Roman power. 

Just as modern scholars’ debate whether grand strategy is a buzzword or a meaningful concept, it is worth considering if the term “ecuneme” could be relevant today. A brief case study of Roman frontiers shows that their actions were guided less by an overarching blueprint or strategy and more by their universal world view. Today, scholars debate American grand strategy, but if there is a strategy it has stayed remarkably consistent across administrations and even essentially unchanging according to critics. It is an approach centred on primacy, military preponderance, and the projection of a liberal hegemony. It is this liberal guiding vision which suggests ecuneme is still a relevant term today. The liberal ecuneme is a world view built on progress in which the spread of open markets, democracy, and human rights are universal and any disruption to the liberal vision is portrayed as backwards, morally corrupt and irrational. This ecuneme can be seen with the way that Russian war with Ukraine has been greeted by Western elites with almost ‘jubilant applause’ for the return of old transatlantic certainties and the confirmation of a world view of liberal freedom against tyranny and autocracy. The Ukrainian conflict has become interpreted as one of competing worldviews and in doing so only encouraged Western elites to double down on a teleological belief of liberal expansion through seeking to hasten the enlargement of NATO and the European Union. According to the philosopher John Gray, the continuing spread of liberal values is an illusion that fails to recognize the isolation of Russia also means the end of liberal globalisation and is likely to harbour a new age of disorder. The result is that the US continues to follow a mission of primacy and universal ideals, rather than one of restraint and realpolitik. These actions by the West therefore appear less as a grand strategy focused on the national interest and strategic incentives, but a world view, or ecuneme devoted to liberal universalism.