A historicisation of war

War remains a constant concern to International Relations (IR). While it is sometimes taken to be an eternal phenomenon (Gat 2017; Gilpin 1983; Waltz 1959), constantly present and threatening the international system, most nonetheless recognise that it is evolving matter which plays out differently and happens for different reasons at various points in time and space (Holsti 1991; Vasquez 1993). In some traditions of thought, war has changed so much as to be unrecognisable (Van Creveld 1991), even having undergone so much revolutionising change that it now makes sense to distinguish between ‘old’ and ‘new’ war (Kaldor 1999). Many are thus aware that in a cross-temporal perspective, war has been different things at different points. It is common to limit one’s analysis to a delimited era, and one of the more long-term is covering ‘the modern global system (1495 to the present)’ (Vasquez 1993: 7). While including that whole period in the modern global system is questionable in the light of more modern periodisation (see, for instance, Buzan and Lawson 2015), this article accepts the basic intuition that the phenomenon called war varies across history. As opposed to several well-known typological programmes, notably the Correlates of War project, which builds its empirical classification of wars on pre-assumed relationships between war and order (Sarkees et al. 2003; Sarkees and Schafer 2000), this article approaches this relationship too, as variable. The novelty of this article lies thus not in new insights about the ontology of war as such, but in the relationship between war and order across time.

In order to historicise the relationship between war and order, I will draw on English School theory. This theory conceptualises current international relations as taking place within not only an international system, but a society of states, or international society. That image is useful shorthand for saying that states do not coexist in a lawless anarchy, but that they consider themselves bound by some minimalist rules to facilitate coexistence, and share in the work of common institutions (Bull 1977: 13). Those institutions are, importantly, not the regimes and organisations studied by liberal institutionalists, but more fundamental practice-based social facts routinely reproduced by states’ representatives. Bull’s (1977) list of institutions includes management by the great powers, diplomacy, international law, the balance of power, and war, but newer contributions have added other institutions as well. Most importantly for this article, however, is that war is usually taken to be an institution of international society when seen from an English School perspective. This institutional status means that war has a constitutive function for the belligerents; that it is in principle taken to be rule-bound; and that deviations from the rules require justification.

While within the larger discourse of war and peace, it is clear that war can be different things and come about for different reasons and in different ways, the English School has a perhaps misleadingly simple understanding of war ‘in the strict sense’. According to Bull (1977: 178, emphasis added), ‘We should distinguish between war in the loose sense of organised violence which may be carried out by any political unit (a tribe, an ancient empire, a feudal principality, a modern civil faction) and war in the strict sense of international or interstate war, organised violence waged by sovereign states’. Yet, this delimitation has been increasingly questioned in recent years (Keal 2017; Pejcinovic 2013; Williams, 2023; compare Jones 2006: 167). Bull seems to represent an orthodox position, delimiting war to mean only war between states, which is problematic because of the Eurocentric and presentist assumptions on which it builds. Not only does it exclude important instances of war in the past and present, but it also closes the inquiry to potential futures which may look very different from the present.Footnote 1

‘Within the modern states system only war in the strict sense, international war, has been legitimate; sovereign states have sought to preserve for themselves a monopoly of the legitimate use of violence’ (Bull 1977: 178–179). This is true in the sense that not all violence for political purposes is war in a conceptual meaning, but it is clearly also a problem in the Eurocentric approach it betrays, wherein war among other political units seems to be overlooked, or its destructive capacities trivialised. Pejcinovic (2013) and Keal (2017) have both argued that, if we fall in the Eurocentric trap of thinking about war only ‘in the strict sense’, important wars might fail to be recognised as ‘real wars’. The question to answer in this article is therefore how to understand war in a way which is useful to the English School framework as well as beyond it, but which eschews the earlier Eurocentrism and is applicable both across time and across space. The missing piece is arguably accounting for the relationship between war and order, so that the different kinds of wars that happen in different orders become visible. I draw on Adam Watson’s work to do precisely this.

In The Evolution of International Society¸ Watson built a simple analytical devise with which to capture the entirety of (then) known history of inter-polity interactions. His claim is that all inter-polity interactions can be usefully analysed as approaching one of four types of order, visualised as positions of an imagined pendulum: empire, dominium, hegemony and multiple independencies (Watson 1992: 13–16). Watson argues that the two extremes of the swing should be understood as ‘theoretical absolutes, that do not occur in practice’ (Watson 1992: 13), or ideal types; there has never been a perfect empire or a perfect system of independent units, and most historical systems have tended towards hegemony. In addition to this qualification of Watson’s, it could be argued that the pendulum’s intermittent positions, of dominion and hegemony, are also theoretical absolutes. Not because there have not been any historical hegemonies or dominions, but because the systems and relations are in a constant process of change, so that they cannot be classified as one or the other without glossing over their nuance or forcefully holding them constant. Watson also seems to be aware of this although he did not press the point: ‘No known system remains fixed at one point in the spectrum’ (Watson 1990: 105). In this piece, I am not drawing on the pendulum analogy as such, which seems to imply a movement that is too regular and nomothetical for my purposes, but only on Watson’s conceptualisation of historical systems as ideal-typical understandings of order.

One might legitimately wonder whether dividing history up in such rudimentary categories is even a meaningful exercise. For Watson, the answer is clearly affirmative. He underlines that we should ‘be careful not to say that the complexity of history makes the enterprise of drawing distinctions a useless one’ (Watson 1990: 104). The risk of imposing coherence and temporal regularity on something that is highly fluid and irregular must be measured against the utility of constructing devises that enable researchers to compare and classify occurrences over time. Overestimating continuity and regularity in history is a very real risk; yet, what might be understood as dramatic simplifications can be very useful for theorising, or what Bull referred to as ‘empirical generalisations’ (Bull 1966a: 371). While it is important not to lose sight of the fact that a neat figure necessarily obscures complexity, it can still be a useful analytical tool. As such, it is a device designed to achieve analytical leverage, not an accurate description of history.

Formulating simple analytical categories with which to impose some coherence on a messy human history enables researchers to study phenomena and processes comparatively across time. Watson is not the only scholar in the English School tradition to do this (see, for instance, Buzan and Schouenborg 2018; Keene 2009), but he was an early mover, and unusually explicit about it. While there is necessarily more to separate, say, systems of multiple independencies (what English school scholars usually call international societies) over time, than to unite them, it can be enlightening to see them both as cases of one and the same class of phenomenon, i.e. as multiple independencies. This argument is at the very basis of the social-scientific enterprise.

These caveats and disclaimers apply to Watson’s systems, and they also apply to the present article, in which a systematisation of war within and between orders will be presented. The primary aim is to nuance our understanding of war by getting war out of its ‘Westphalian straightjacket’ and theorising it in a way which is at the same time cross-temporal and cross-cultural, by drawing on Watson’s conceptualisation of successive orders. War can, which is the central argument, be understood as a common label for several different classes of phenomenon depending on the order in which is plays out; distinguishing between different kinds of war in history will provide a better grasp of the ordering and disordering potential of war, in the present and in the future. Our understanding of war as an ordering and disordering phenomenon is very limited by the Eurocentric and Westphalian lens which is usually applied to it. By approaching war from a wider perspective, its disruptive potential as well as its ordering practices will be more clearly visible. As a secondary aim, the article also illustrates the use of ideal types to classify a messy empirical reality, and in passing clarifies Watson’s methodological contribution.

Order and international society

Necessarily, war is and has been a common topic in the study of international politics generally, and also in the English School tradition drawn on here (Bull 1977; Buzan 2004; Holsti 2004; Jones 2006; Lees 2021; Luard 1986; Pejcinovic 2013; Suganami 1996). Its relationship to order is, however, more rarely discussed and often focused on its role in maintaining (current) order (Bull 1977: 178–193). Watson (1992) discusses a succession of orders, but does not explicitly theorise the role(s) of war therein; rather, war is treated as part of the substance of those orders, a choice presumably also reflecting the sources to which Watson had access. Order here should here be taken to mean the presence of as a social system ‘in which shared norms, rules, and expectations constitute, regulate, and make predictable international life’ (Goh 2013: 7). While the word ‘international’ in this definition hints that it is developed with the contemporary ‘anarchical society’ in mind, it is wide enough to cover also other orders along Watson’s spectrum. The presence of order does not per se exclude the possibility of war, understood in line with Bull’s definition above as organised violence carried out by political units. Rather, war within an order is supposedly following a minimal level of rules, while war outside of such order can be completely lawless.Footnote 2

Within international society, a sort of order which according to English School theory has occurred a handful of times in known history, war has been described as follows:

‘On the one hand, war is a manifestation of disorder in international society, bringing with it the threat of breakdown of international society itself into a state of pure enmity or war of all against all. The society of states, accordingly, is concerned to limit and contain war, to keep it within the bounds of rules laid down by international society itself. On the other hand, war—as an instrument of state policy and a basic determinant of the shape of the international system—is a means which international society itself feels a need to exploit so as to achieve its own purposes’ (Bull 1977: 181).

As we go back in history, orders were fewer and far between, as communication was limited to polities of geographical proximity. Order was then a regional phenomenon. For instance, around 1490, several orders coexisted in the Afro-Eurasian regions, while orders in Oceania, the Americas and other parts of the globe were less integrated (Phillips 2017: 44).Footnote 3 In our modern, globalised world, however, order is mainly understood by the English School to be common across the globe. This is somewhat in contrast to the literature on multiple orders (Flockhart 2016; Flockhart and Korosteleva 2022). Disorder, then, is simply conceptualised as the absence of such organising principles, either because the polities in question have not established them, or because the contacts between them are too scarce to warrant it (compare McKeil 2021, 2022). In turn, this means that disorder does not necessarily imply chaos and the war of all against all—it might also mean that polities do not interact, or interact so little that they do not follow any preconceived rules when they do.

Historically, order has sometimes broken down into chaos or ceasing interaction—perhaps because of great plagues or natural disasters. More commonly, however, one order has morphed into the next so that it is only in retrospective that we can, somewhat arbitrarily, draw a line between one order and the next (Watson 1990: 104–105). So, for instance, did parts of present time Russia over the time span of half a millennium move from being part of the Mongol empire, to forming its own suzerain system within that empire, to becoming a member of the European society of states in the nineteenth century (Neumann 2014; see also Neumann in this special issue).

In this reasoning, war might take several shapes. It may happen in disorder—that is, without common rules and understandings uniting the belligerents, such as if two polities encounter for the first time and consider each other enemies from the start. More often, war happens within an order and is then guided by preconceived categories of lawful conduct. Alternatively, it can happen between members of one system or society and non-members of that society, yet fringe-members of that same order, such as between agrarian empires along northern coast of the Indian Ocean and nomad peoples from the Eurasian steppe—what Phillips (2017: 48–53) calls the Indosphere and Saharasia—as has been the case during large stretches of history. The same people and territory can belong to different orders over time; or interact with more than one order at the same time (for examples, see Suzuki et al. 2014).

In current English School theory, the relationship between war and order is sometimes overlooked, possibly because the existence of international society, and therefore of order, is taken for granted. Discussions about war, while nuancing the idea of war ‘in the strict sense’ in important ways, tend to take place within an ordered context (Williams, 2023; Keal 2017). Moreover, war is sometimes understood through what might be called a ‘solidarist hungover’, in which war was taken to be disappearing and being replaced by collective enforcement of rules (Knudsen 2019; Wheeler 2000; Bull 1966a, b). This arguably leads to a difficulty of grasping the return of old-fashioned war, more often conceptualising political violence as great power management (Hadano 2023; Jakobsen & Knudsen, 2022).

The rules of war

In Bull’s The Anarchical Society, discussing war within an international society, war is, somewhat confusingly, simultaneously taken to be both one of the common institutions that maintain international order, and a sign of disorder in international society as in the quote above. One way to interpret this is as ‘taming the sovereigns’ (Holsti 2004), namely, restricting and regulating war so that it is, to some extent, rule-bound conduct. In short, war as an institution, that is a rule-bound activity, is not system-threatening (however, morally deplorable it may be), while war as disorder is. In Bull’s (1977: 179) terms: ‘We are accustomed, in the modern world, to contrast war between states with peace between states; but the historical alternative to war between states was more ubiquitous violence’.

In Bull’s account, war is also an instrument that can be harnessed for international society’s common purposes; this contrasts to the conceptualisation of war as solely an instrument for states to advance their national interests. Instead, war can be used as means to punish an offender or enforce international law, both foundational ideas in collective security and in humanitarian interventions. ‘From the perspective of international society, war retains its dual aspect: on the one hand, a threat to be limited and contained; on the other hand, an instrumentality to be harnessed to international society’s purposes’ (Bull 1977: 191).

The distinction between war as a pillar of order and war as system-threatening disorder is notoriously difficult to draw empirically, as the activities of war are always chaotic and violent, but Phillips (2011) provides some input in his book on religious transformation. He studies the collapses of order in European mediaeval Christendom (15th to seventeenth centuries) and in the Sinosphere (late 19th to twentieth centuries). His suggested tipping points for those orders are on the one hand the spread of new ideational goods which overturn the legitimacy of the ancient order, and on the other hand new military technology which increases the potential for violence. This combination, in both of his studied eras, proves powerful enough to upset reigning orders, and disorder ensues. In this way, war is associated with breakdown of order, but the lawlessness of those wars seems to be not so much a threat to order as a consequence of order breaking down.

In Nexon’s (2009) study of early modern Europe, ca 1477–1648, war is also endemic. It covers the transition period of the Protestant reformations and building of the sovereign states often taken for granted. But there was also a distinct fight against outsiders of the European society, namely various wars with the Ottoman Empire. The various European princes sometimes made deals with the Ottomans in order to be able to focus their resources on internal wars, and sometimes they overcame their own rivalries to join forces against the Ottoman outsiders (Nexon 2009: 132, 160–169). ‘Yet, [the Ottoman Empire] was not part of the European international society, and disdained that society’s rules, institutions and peace settlements. Instead, the Ottomans developed a separate regulatory code of conduct with the European states, known as capitulations; which were largely prescribed by the Ottomans in the heyday of their power, but later modified by the Europeans in their own favour when they became stronger’ (Watson 1990: 101). In a less Eurocentric account, Göl (2014) discusses how the Ottoman Empire was, in the centuries surrounding the 30 Years War, the centre of its own international system, in which European entities were at most fringe members.

War as in international institution

It is Standard English School procedure to think about war as an institution of (Cold War) international society. Here, it is extended to being conceptualised as an institution of any order. Bull’s justification for calling war an institution of international society is that it, in certain conditions, contributes to upholding order among the states of that society. It does so by consisting of a defined set of practices, along with a discursive legitimation consisting of norms, beliefs and expectations (Friedner Parrat 2017: 628). Bull (1977: 179) thus distinguishes between ‘war in the material sense, that is actual hostilities, and war in the legal or normative sense, a notional state of affairs brought into being by the satisfaction of certain legal or normative criteria, for example that it be recognised or declared by competent authorities’. A similar argument is advanced by Holsti (2004: 25), who calls war a ‘procedural institution’: ‘composed of those repetitive practices, ideas and norms that underlie and regulate interactions and transactions between the separate actors’.

Bull also notes that ‘If we are speaking of war in the legal sense, the distinction between war and peace is absolute […] War in the material sense, on the other hand, is sometimes hard to distinguish from peace’ (Bull 1977: 179). Similarly, Kaldor (1999: 24) writes about the codification of the laws of war, and remarks: ‘While these rules were not always followed, they contributed importantly to a delineation of what constitutes legitimate warfare and the boundaries within which unsparing force could be applied’. Notably, though, these observations are valid for interactions within international society, not across history, and not for interactions between members of different orders.

The upshot of thinking of war as an institution is that the norms, beliefs and expectations only apply to insiders. Anghie (2005: 35) discusses how this came into play in the European experience of colonising other parts of the globe, and specifically points to how non-Europeans were defined as outsiders under legal positivism so that the intra-European standard of conduct did not apply in encounters with them. He also addresses how this very encounter between non-Europeans and Europeans contributed to the latter conceiving themselves as parts of a common civilisation—which excluded the former (Anghie 2005: 106). In earlier orders, the idea of war as a common practice among the members means that war may be rule-bound (as convened by sovereign entities in a formally anarchical system; or more frequently, as enforced by the hegemon or empirical centre) within a system, but not against outsiders.

A framework for classifying war over time

Working through the English School account of war as an institution of international society, two questions thus arise: first, when is war correctly treated as an institution, and when is it an indication of disorder? Second, among whom is war an institution, and what happens when outsiders of a given international society/system are implicated? Both of these questions will be discussed in turn, drawing on Watson’s The Evolution of International Society (1992) for the systematisation of various types of international orders over time. Watson’s division of world history into separate international orders will be helpful in sorting through both how order and disorder play out in various contexts, and who is an insider or outsider of a given system.

Order/disorder

In the shortest version of the present argument, war within orders (systems in Watson’s sense) tends to be institutionalised, and some forms of order, notably empires, may tend to be more peaceful, as long as the distribution of power within them is not disputed. At the other end of Watson’s notional pendulum swing, multiple independencies may be war-prone almost as per a Hobbesian logic of anarchy (Wendt 1992), with the potential for war of all against all. To counter this tendency, participants in these systems may over time develop rules to institutionalise war. In systems in between, having one power strong enough to lay down the law for others—Watson’s definition of a hegemon—would typically be conducive to more peaceful interactions, but only as long as the hegemon can uphold its dominance. This highlights the intuition emphasised by realism and power transition theory, that times of disputed power and shifting balances may be violent and war-prone. Yet, transformations can also be gradual and unremarkable. As a general point, however, the presence of order, be it in the shape of empire, dominion, hegemony or multiple independencies, supposedly generates more peaceful interactions than the absence of such order.

Members/non-members

The next question is what sort of units can be participants in an order of Watson’s kind. Very often, clearly, it has not been entities that resemble of sovereign states mutually recognising each other’s independence. Instead, the entities of Watson’s systems have had all sorts of, often unequal, relations with each other. The interesting point is not whether these orders were made up by states or other political units, but who was recognised as a member, and in what ways membership in that order contributed to constituting an entity. It is not difficult to imagine how territories and peoples, by being integrated in an empire, for instance, gradually took on the identity of a separate entity within that empire as their interaction with other groups or entities with the empire increased (see, for instance, Hoffmann 2023). In modern times, arguments about how peoples and territories have been moulded into the format of sovereign state by international society are common, particularly in the context of colonialism and decolonisation (Jackson 1993).

In war, the question of whether the opposing side is part of the order in question or whether it is an outsider to it (and hence perceived to be some other type of entity) is absolutely central. In principle, outsiders are not bound by the common rules and institutions, which also then affects war and ideas about legitimate warfare. Jones (2006: 163–164) quotes Bull stating that war is ‘a clash between the agents of political groups who are able to recognize one another as such and to direct their force at one another only because of the rules that they understand and apply’. This makes it central for a belligerent to be able to determine the membership status of the adversary.Footnote 4

Perhaps the first example that comes to mind for a present reader is the encounter between Native Americans and European settlers and colonisers (Crawford 2017; Keal 2003). Early European international lawyers discussed not simply whether Native Americans were members of the same family, so that international law should be applicable to them, but also, shockingly from today’s point of view, whether they were ‘natural slaves’ (Pejcinovic 2013: 2). Jones (2014) points out how the most important relationship between Native Americans and newcomers was actually not the one between Natives and Europeans, but the one between Natives and settlers, ‘creole populations’. That their interactions, including conflicts, were of paramount importance in building a ‘distinctly American international society’, causing several native peoples to seek support from the European colonialist against the settler population, is often obscured by applying a Eurocentric lens to this interaction (Jones 2014: 135).

But there are other examples of insider and outsider distinctions, too: centuries of wars between Christians and Muslims have been framed in terms of combatting the faithless or infidels (Pejcinovic 2013: 42–51). Interestingly, this has been interpunctuated by periods of rather peaceful coexistence, and even strategic alliances, notably between emerging European composite states and the Ottoman empire (Naff 1984; Nexon 2009: 132); and the geography and extension of the Ottoman empire meant that it had important interactions with several regional orders simultaneously (Göl, 2014). Sixteenth and seventeenth century relations around the Mediterranean Sea are in this respect usefully reframed by Göl (2014: 42–45) as ‘Europe on the margin of the Pax Ottomana’.

As shown by Phillips (2017), the story of human interaction at the outset of the sixteenth century was one about great civilisations around the Indian Ocean interacting with each other within several separate but interconnected orders, and fighting both internally and with those perceived as outsiders, mainly from the Eurasian steppe. In an even wider perspective, Buzan suggests that this image holds true for most of human history since the neolithic revolution: great agrarian empires or other societies close to the coasts of the Indian Ocean and in the deltas of mighty rivers coexisted, and fought amongst themselves as well as against ‘barbarians’ from the Eurasian steppe. This is notwithstanding that those ‘barbarians’ from the steppe were often more technologically advanced than their adversaries and brought inventions such as the domesticated horse, the stirrup and the chart (Buzan 2023; see also Neumann 2014).

Important for the present conceptual enterprise, however, is the point that international orders have in general had an outside. Some of them were isolated, certainly, and never ventured into contact with the outside, but to many of the peoples involved, the distinction between insiders (people that resemble of ‘us’) and outsiders (‘barbarians’, ‘savages’, or ‘infidels’) made sense. Yet, in today’s globalised society, there is no formal outside. There are hierarchies, formal and informal, but no legitimate outsiders. To be able to talk about outsiders now, therefore, attention needs to be turned to the outsiders within (Phillips 2011: chapter 10).

Four ideal types of war

Overlaying the dimension of order and disorder with that of members and non-members produces four ideal types of war, to which real, empirical war can conform more or less (Fig. 1). In this particular taxonomical enterprise, the line-drawing is further complicated by the possibility that the two dimensions interact. As has been argued above, when international order is present, war as an institution might contribute to constituting members within that order, and also to delineating frontiers between insiders and outsiders. In large parts of history, parallel orders have been present in time–space, and war across orders (rather than within them) contributed to delineating them—but over time also often to integrate them into a common order.

Fig. 1
figure 1

Ideal-typical representation of war

Full size image

In addition, in the extreme case when no sort of order is present, the distinction between members and non-members collapses, as there can logically be no members if there is no order. It can be useful, therefore, to imagine the boxes in the figure below rather like parallelograms than like the squares with right angles schematically depicted here; the bottom-left scenario of members and disorder cannot be completely deplete of order, as that would exclude the idea of membership. Yet, it can be closer to disorder than to order, and in that sense fall closer to the bottom of the y-axis than to its top.

Historically, cross-over scenarios have been common, both relating to who is a member of an order at any given time, and relating to distinguishing between order and disorder at a given moment. For the fuzziness of membership status, consider, for instance, the relationship between early modern Europe and the Ottoman Empire, which involved ‘capitulations’, a ‘separate regulatory code of conduct’ (Watson 1990: 101). There were some shared rules, but not generally taken to amounting to membership. Also, Russia’s relations to Europe in some periods (Costa Buranelli 2014; Neumann 2014), as well as Africa’s relations to Europe (Quirk and Richardson 2013), have been ambiguous and shifting. Another example is the Greek city states’ relationship to Persia (Watson 1992: 43–46). All of these represent a dynamic insider/outsider perspective of ongoing transformations where it is hard to determine who is a member or non-member of a given order at a given point in time, especially in long historical retrospect.

It is equally difficult to draw a line between order and disorder in a given empirical situation. What seems like orderly relationships between units from a distant observer’s perspective might be experienced by participants as continuous or successive crises. Carr’s (1946) most famous work in IR is called The twenty-years crisis but in retrospective, the time-period between the two world wars seems characterised rather by inter-European order than by disorder. Likewise, if the period of European upheaval in the transition from a feudal system to a system of independent states went on for a century and a half, as argued by Phillips, that covered several generations of monarchs and statespeople, and was probably understood as business as usual for them, as well as for most ordinary people of the era. The point here is not to give exact historical accounts but, like Watson, to abstract enough to be able to analytically differentiate between eras.

Order-sustaining war

When we talk about war as an institution, it is this category of war that we typically envisage: war among insiders, who share common understandings of rules and norms, making war—paradoxically—an orderly phenomenon. Yet, empirical wars have never lived up to this image. ‘Even when applied to the experience of modern Europe up till the post-Napoleonic period, out of which Clausewitz’s analysis grew, it was a recommendation as to how wars should be conducted, not an accurate description of how wars were actually fought’ (Bull 1977: 180). In addition, when Kaldor (1999) makes her case for the difference between old and new wars, the Eurocentric image of Clausewitzian war is what she means by old war.

One can imagine similar images being applied to wars within other types of orders, such as in the pre-globalisation Islamic order (Watson 1992: 11), the Sinosphere before the Opium wars (Phillips 2011: 6–7) or the First Nations in North Americas (Crawford 2017). These orders took various shapes (multiple independencies, empires, dominions or hegemonies), but they were ordered. As such, they made a clear distinction between insiders and outsiders, although even those must have been rather fuzzy at the borders due to perpetually ongoing transformations.

The primary characteristic of order-sustaining war as an ideal-type is that war is part of the normal operation of relations, and assumed to happen, either from time to time or continuously. Its occurrence does not immediately denigrate the existence of order, but serves to clarify hierarchies or rules within that order. In a perverse way, it can also serve to confirm the membership of the order, as participation in the institution of war as a regularised occurrence rather than as lawlessness, shows belligerents’ acceptance of very basic common rules. Notably, it is not the occurrence of war that is a sign of some sort of order, but its regulation through common understandings of how to fight it. Violence as such is supposed to be an ever-present possibility.

Order-delineating wars

It is fitting to think of colonial expansion as a quite different beast from intra-European integration. While the European international society in the eighteenth and nineteenth centuries grew to emphasise toleration among its members, it instead emphasised spread of its preferred version of civilisation in its dealings with those whom it saw as outsiders. ‘Within Europe, the leading purpose of international order was to promote peaceful coexistence in a multicultural world through the toleration of other political systems, cultures and ways of life. […] Beyond Europe, however, international order was dedicated to a quite different purpose: the promotion of civilization’ (Keene 2002: 98). Keal (2003: 85) writes: ‘What was applicable to relations between European states was not necessarily appropriate to relations between those states and other civilizations’. In Anghie’s (2005: 65ff) account, the problem of how to write the doctrines distinguishing between allegedly civilised and non-civilised peoples, ‘which could legally account for [the] expansion of Europe’ was the main task of legal positivist scholars in the colonial empires.

This means that toleration should be maintained in Europe with diplomacy, balance of power and international law, and that war should be an exception, whereas in other parts of the world a much higher level of coercion was applied to pressure communities and suppress their allegedly uncivilized ways of life. Importantly, this led to an integration within the European core, involving the self-understanding as civilised (Keene 2002), and was even instrumental for the evolution of the European international society as such (Anghie 2005; Welsh 2017). Yet, in these accounts, extra-European orders, too, were orders, albeit orders with different purposes.

The prevailing Eurocentrism, which the classical English School shares with large parts of IR, easily distorts one’s view to seeing European international society and its outsiders, but obviously these perspectives can equally well be turned around to see native American, African or Asian societies and intruding European outsiders. Needless to say, there were also numerous interactions among insiders and outsiders in which Europeans played no part whatsoever, for instance, between societies on the African east-coast and Islamic outsiders, what Phillips (2017: 55–57) calls the Islamicate.

Additionally, it is questionable to argue, as Keene does, that war between Europeans and non-European was orderly. What comes to mind is instead an image of indiscriminate killing, exploitation and abuse. But quite like the non-ideal-typical Eurocentric image of war, practice and normative recommendation were two rather separate things. One of the normative recommendations was the idea of trusteeship, a stage-theory according to which non-Europeans had not yet arrived at the same stage of development and ‘civilisation’ as the Europeans (Anghie 2005; Bain 2003; Gong 1984). Therefore, they could not be admitted as insiders of (European) international society, and war against them was presumably then not bound by the same rules. Yet, there were, at least in Keene’s account, different rules. Just like in intra-European wars, however, they were not necessarily followed in practice.

Colonial wars are not the only historical example that could come close to the ideal-type of orderly war between insiders and outsiders. Although the usual account dates Japan’s ‘entry into international society’ to 1853 (Suganami 1984), the war between Russia and Japan in 1905 can be seen as an example of a confrontation between an insider of one order and a fringe-member (Zarakol 2010). After beating Russia at its own game, Japan claimed the status of a great power in international society (for an account of the earlier contacts between Japan and representatives of Europe, see Suzuki 2014). Any empire in the process of subjugating a new polity could be counted to this category, as could the Greek city states in their interactions with Persia, Macedonia and Rome (Watson 1992: chapters 4–6, 9). Each of those at different points in time where insiders of the Greek system, outsiders of it, or came to dominate it.

Order-threatening war

The idea of an order-threatening war is that the belligerents are insiders, but that they abandon their common rules and norms, making war in disorder. If we were to have a great-power war today, especially a nuclear war, it would by definition be order-threatening; not only because it would threaten the life-sustaining powers of the planet and the continued existence of humanity. An extreme disregard for the rules of warfare, such as a breaking of the nuclear taboo, would erase all elements of society uniting the belligerents. War as disorder without any outsiders logically offers only this possibility. However, historically, order-threatening wars have not lead to species extinction, but to transformation of order. Two possible outcomes of such wars are either that a new order emerges, or that the old order is challenged but survives.

The Thirty Years’ War is an example of a disordered war among insiders of the mediaeval Respublica Christiana, which in historical retrospect seems to have led to a transition from one order to the next (Nexon 2009; Phillips 2011). The 30 Years’ War itself could be understood as a German civil war, in which other entities, such as the French rulers and the Swedish king, interfered (Phillips 2011: 127–131). But it was preceded by substantial unrest also in Spain, Italy and the Netherlands, and a bloody civil war in France, and followed by a civil war in Britain, in total making for about 150 years of upheaval and successive attempts to create a new order in Europe (Nexon 2009). This period can thus be understood as a drawn-out transformation of one order into the next, with largely the same insiders: mediaeval European Christendom on the one hand and the Westphalian system that started to slowly take shape after the end of the war on the other. Yet, even here, outsiders contributed pressure on the European system, notably in the shape of the Ottoman Empire (Naff 1984).

The other version is when the same order is reinstated after a failed attempt to threaten the system. Watson (1992: 228–229) writes that ‘Napoleon’s imperial order […] carried the European system well past hegemony, and brought much of Europe under his dominion’, thus replacing multiple independencies with dominion. Yet, when focusing on war, the Napoleonic wars were to a large extent following the rules and norms of war as an institution; or at least those were the wars that the foremost writer on war (Clausewitz 2007) had in mind. A better example is World War II where Hitler’s Third Reich in company with fascist Italy and militarist Japan overrode diplomatic efforts to solve the conflict and instead proceeded to force their way through several continents to create regional hegemonies. It can be seen as an order-threatening war, which was finally won by those who preferred the status quo arrangements. It ended with largely the same international society as before the war, but with a substantially extending membership following decolonisation.

Arguably, however, in historical retrospect it makes more sense to include WWII in the transition phase from a Western-colonial international order with a limited membership to a post-colonial international order with global membership, than to see it as the old order reinstated. Keene argues that one of the reasons why the colonial empires fell apart was that their civilising mission became increasingly difficult to defend in the face of the barbaric behaviour by Europeans. ‘[I]t was awkward, to say the least, to affirm the supremacy of the white race over African or Asiatic races, while simultaneously denying the validity of Nazi attempts to demonstrate Aryan supremacy. By projecting civilization against Nazism, its defenders were inevitably calling old assumptions about the racial boundaries of the civilized world into question’ (Keene 2002: 136; see also Anghie 2005: 138).

Order-denying war

The last ideal-type is about disordered wars with no common rules and norms, and, consequently, with an understanding of the opponent as not belonging to the same order. In Kaldor’s (1999) conception of new wars, we see the inclusion among warring actors of many types of agents that are not part of the involved state, and often in direct opposition to the state. This means that they are, by definition, not insiders of international society, as the members of the present international society are states. ‘Indeed, it could be argued that the new wars are part of a process which is more or less a reversal of the processes through which modern states evolved. […] Thus the distinctions between external barbarity and domestic civility, between the combatant as the legitimate bearer of arms and the non-combatant, between the soldier or policeman and the criminal, are breaking down’ (Kaldor 1999).

New wars are, at once, localised and globalised (Kaldor 1999), but not spread in such a fashion that they become order-threatening. Probably, this is due to the limited military capacity of independent military actors in comparison with states. However, there are no guarantees that these wars will remain smaller scale, especially as states with more potent resources meddle in them. States still adhering to international society’s rules and norms somewhat limit the spread of these wars.

Historically, disordered war between belligerents who did not share basic understandings of how war was fought may have been common in the early contacts between civilisations, but must over time typically have become more predictable as communities were confronted with each other’s ways and aims. Moreover, the ‘enemy within’ scenario is probably also applicable also historically, for instance, in the collapse of the Sinosphere or with the rise of Protestantism in Europe (both transformations described by Phillips 2011). It is no coincidence that Phillips devotes the last chapter of his book to the most important threat to international society at the time of his writing: ‘the jihadist terrorist challenge to the global state system’.

Conclusion

Using Watson’s concepts to build a classification system for the relationship between order and war is a counter-intuitively forward-looking enterprise. Although an ideal-typical device such as the one presented above cannot capture much nuance neither in the future nor in the past, it can be useful for categorising broad-brush similarities and differences over time, thus helping to systematise a messy history. The central argument is that it allows for distinguishing between various types of phenomenon, which all happen to be called war, but to which it would probably be a good idea to stick separate labels. What war has looked like in practice has varied immensely with technological development and tactic and strategic evolution (which is well-known by most observers) as well as with different societal configurations (which is more often overlooked).

The inquiry has reinforced the point that there is a major difference between empirical history and analytical categories used to organise that history. It is important not to conflate these levels. When using Watson’s categories, an easy sin to commit is to start to think about, say, the Mongol empire as an ‘actual’ empire rather than as ‘a case of’ empire. In actual history, the long existence of the Mongol empire tells us that it morphed and changed continuously, included various subsystems over time, and had many different sorts of relations with outsiders and fringe-members over time (Neumann 2014). To analytically classify it as ‘a case of’ empire, one needs to keep its actual history at arm’s length, or abstract from it enough to fit it into the category. When Watson is criticised for simplifying history too much, this difference between actual history, and the analytical categories used to impose order on it, might be at fault.

One substantial conclusion that can be drawn from this study, fairly much in line with the intuition of most English School theorists, is that war as an institution has indeed not been continuous throughout human history. Instead, the reconceptualisation of war in this piece allows for a more fine-grained discussion of how war should be understood as different classes of phenomenon depending on how it relates to order in different times and places. War ‘in the strict sense’, understood as an institution, is a peculiar case which is only applicable at certain points in time and space, namely when the members of an order cooperate to uphold certain rules with regard to the conduct of war, thus institutionalising it. Most commonly, these members have not been formal equals, but formed hegemonies, dominions or empires; yet, with some sort of common rules of conduct which have applied to wars among insiders, but not in dealings with outsiders.

War as disorder, that is, without commonly accepted rules, is also a distinct possibility. As for the future, this inquiry points to both the order-threatening and order-denying capacities of such wars. The reason for this is simply that, short of a hostile invasion from space, there are no more classical outsiders of today’s globalised international society. Logically, the modern type of outsiders are those who revolt against states. These can be terrorist groups or freedom fighters, fighting to become parts of international society, or to bring international society down. While this sort of war is doubtlessly sometimes justified from the perspective of justice, it is threatening from the perspective of order. As such, it points to a well-known central tension in international society theorising: the normative conflict between order and justice. The current international society has proven capable of absorbing wars of liberation without breaking, and oftentimes integrated secessionist movements among its members once they have achieved most of the characteristics of sovereign states, but in the long historical perspective drawn on here, justice has been a rather marginal occurrence. More often, secessionists have been struck down violently, or managed to break up structures such as empires, thus contributing to international orders falling apart or morphing into another system.

Newer sources and less West-centric thinking also seem to invalidate Watson’s thinking of successive orders as analogical to the swing of a pendulum. Instead, an image of a plurality of co-existing orders gradually morphing into one global order seems a more promising historical narrative. To some extent, also the classical English School writers were aware of this—after all, Bull and Watson (1984: 1) edited The Expansion of International Society, which starts from the assumption that international society replaced other orders which already existed, and sets out to map that process. Although this was a vastly superior ambition, compared to the contemporary research which rather projected the Cold War international system back in time, the process of revising these starting points and correcting the West-centric perspective employed is an important and ongoing project in current English School research. Hopefully, the reconceptualisation of the relationship between war and order advanced in this piece can also bring a small contribution to that project.