Reasons for War in Premodern Societies

Wars do not happen without reason, even if some reasons may seem stupid to modern readers. This is important, because objective of the war also determines the conduct of the war. War whose objective is completely conquering the enemy country will not be fought in the same way as a war whose sole objective is capturing slaves. No country, government or organization is evil simply to be evil – evil people are typically convinced they are doing good! – which means that a war has to have some purpose to achieve. Establishing believable reason for the conflict that drives the story can help in making both the world and the story more internally consistent and immersive.

Scarcity of Resources

Scarcity of resources is a common reason for war. This scarcity does not need to be something critical, though it may be. It could be lack of farming land, or merely attempt to control the lucrative trade route. In Stone Ages, groups of people that ran out of food would take their neighbour’s food. Even in Middle Ages, if one area suffered from bad climactic conditions, solution was often to just go and take neighbours’ food.

Migration

Whenever there is a mass migration, there is a war. Western Roman Empire was destroyed by mass immigration of barbarians, and Mexico lost Texas to mass (and planned) immigration of American settlers. Rome was capable of dealing with different ethnic groups normally – the Empire essentially allowed each group to live as usual, follow their own laws and gods, so long as they paid taxes and obeyed Imperial authorities. But settlement of migratory barbarians placed strain on the system, and while Rome did its best to integrate the newcomers, this proved impossible in the long run. It should be noted here that Western Empire dissolved despite the fact that barbarians generally remained rather loyal to the Emperor – at least on paper.

(Note that this migration itself was caused by expansion of the Chinese Empire. Huns had been raiding China for a long time, until in 400 BC Chinese Emperor got tired of it and directed his generals to chase them away. They did so, which caused a chain reaction of westward migrations by barbarians – with Huns themselves showing up in the west in 400 AD).

Loot and Plunder

Of course, resources need not be scarce for people to want to take neighbour’s resources. In general, the more people have, the more they want. Vikings are a good example of a group whose primary goal was plunder: in fact, name “Viking” itself means simply “raider”. That being said, Vikings did settle elsewhere – see “Land Grab”. It is thus unsurprising that majority of medieval armies – with the exception of the Byzantine and Arab armies – were usually small.

Of course, things could escalate. If a local raid (say, between counties) hit more than one county, then the local war could spread to the next level. And on occasion, this would go up the chain until it involved the entire kingdom.

And this could easily come to place that war would feed itself. In order to defend against the Ottoman expansion as well as opposition from within the kingdom, Matthias Corvinus decided to form a standing mercenary army – first of such type in Europe. But this army was runiously expensive for the resources of the kingdom, and so he was forced to wage basically perpetual wars in order to pay for the army’s upkeep.

In fact, out-of-job mercenaries tended to turn to looting and plunder, becoming in essence well-organized bandit gangs. Best way to deal with the problem was to hire them again and set them loose against one’s enemies.

Slaves

Slaves were another form of loot and plunder – and perhaps one of the earliest forms. Native African tribes used to wage perpetual warfare to enslave each other. This resulted in development of lucrative business when Europeans arrived, with tribes selling captured Africans to European and North American slavers. And while more developed societies such as the Roman Empire rarely waged wars solely for purpose of capturing slaves, slavery as part of motivation as war still should not be discounted.

Land Grab

As authority in feudal system was based on land ownership, taking more land was a big driver in expansion. Otto the First pretty much drove eastwards expansion of the Holy Roman Empire simply to gain more land for his nobles. More importantly, systems with primogeniture mean that all lands go to the eldest son. For younger sons then, the only way to get more land is to conquer it.

Trade

Trade is a major war maker. Trade powers could make war to force other countries to open ports and borders to their trade (famous examples are the Opium Wars). Other times, two countries might fight for control of a particular trade resource, or a trade route. Too many restrictions on trade can cause war as countries seek better economic positions, but too few restrictions also leads to greater probability of war as greater number of potential trade partners reduces bilateral dependance and thus potential cost of waging war.

Geography

Sometimes, a country or a group of people will be attacked because they are located on an important geographical location – see the point about trade routes above. This could also be an important defensive position (e.g. control over a mountain pass), or a potential threat to larger state’s territory their location makes them.

Belief Systems

Religion or political ideology can frequently be a major cause for war. This is most obvious with belief systems which claim to hold universal truths. Historically, monotheistic religions such as Judaism, Christianity and Islam had engaged in offensive warfare against unbelievers, either to wipe them out or to convert them to their own religion (Islam being the most obvious offender). Genghis Khan believed it was his destiny to conquer the world for his god, Tengri. In more modern times, secular belief systems which likewise claim to hold existential answers have also caused major wars – obvious examples being communism, nazism and fascism, but also liberalism.

Even when religion or political ideology are not a factor however, cultural differences can still lead to a war. Different beliefs and ways of thinking can cause misunderstandings which may either slowly snowball or suddenly explode into open warfare.

Historical Animosities

Historical animosities are another reason. National mythology often shapes attitudes and even policies. One of major reasons why Hitler could start the Second World War was belief in Germany that country had been betrayed, and also exploited by the victors. And the main reason why ideologies such as Nazism and Fascism were able to spread throughout Europe was the fact that Soviet Union had spent period of 1917 to 1922 invading anybody it could reach (Estonia, Finland, Poland, Latvia, Lithuania, Armenia, Azerbaijan, Georgia, Ukraine) and remaining 17 years until 1939 it spent financing various Marxist (Bolshevik) uprisings, revolutionary movements and terrorist groups throughout Europe and wider.

It is important however to understand historical, social and cultural factors which had shaped these animosities, and how they continue to do so in the present.

Historical Claims

Any self-respecting country that loses territory due to enemy invasions is not going to recognize the loss so long as any hope of recovering the territory remains. And this can cause wars. After Western Roman Empire got dissolved by mass immigration of barbarian tribes, Eastern Roman Empire was a natural successor to its claims. At first the East recognized situation on the ground as a de facto reality, but never de iure accepted the loss of the Western Empire. This eventually led to Emperor Justinian attempting to reconquer the West – something he may have succeeded in if not for the Justinianic Plague.

Quest for Glory

Sometimes, wars will be caused merely by people seeking glory. While such motive may seem ridiculous to modern mind, it should not be forgotten that premodern wars were nowhere as destructive as wars of modern times. Back in Antiquity and Middle Ages, war was often seen as a way to gain glory, be it for individual or for the group. In many cases, warfare was almost ritualized. Such honor wars were usually on a much smaller scale than economically or politically caused wars.

Natural Disasters

Volcanoes, hurricanes, but also droughts can leave entire areas uninhabitable. When this happens, a mass exodus ensues. And this exodus can easily take on nature of an invasion (in fact, any large migration is a de facto invasion).

Corrupt Rulers

Rulers or governments (including democratic ones!) can become corrupt and start considering only the interests of a single group or class of people. Once that happens, government may start a war for interests of a particular group or even an individual, or else a rift may open in the country that will lead to a civil war.

Legal Confusion

Wars could easily be caused by legal confusion. Especially feudal legal relations were often complex. For example, after William of Normandy conquered England, he became king of England. But since he was still duke of Normandy, he was technically a vassal to king of France. This was bound to cause trouble. Situation repeated itself later, with Henry V – then King of England – being also the Duke of Aquitaine, and thus bound to swear fealty to the French king.

Succession Struggles

Above would often lead to succession struggles as well. If one kingdom followed inheritance by primogentiure but other had patrilineal inheritance, then a king of one kingdom could easily consider himself to be a king of second kingdom as well, yet be denied. This was the cause of Hundred Years War between England and France, and also why Coloman managed to secure support of Slavonian nobility before attacking southern Croatia (which led to death of king Petar Svačić).

In fact, various legal confusions related to succession were probably the most frequent cause of warfare between kingdoms.

Power Struggles

Barons always looked to restrict power of the monarch, while monarch sought to expand his own powers. While this resulted in something of an equilibrium which allowed greater freedoms, it also meant that king could begin a war simply to redirect barons’ attention elsewhere.

In a feudal system power of the central government also tended to lapse over time. Lack of administration meant that monarch often had to show up in an area in person, with the court essentially travelling the kingdom in a manner of travelling circus. This presence was not always welcome because it was expensive, but expenses were also part of the point – as barons had to host the ruler, they would be too busy planning how to pay the enormous costs which came with the honor to think about rebelling. Further, because authority of the monarch was based on technically land grants, as monarch ran out of land so his authority weakened.

Holy Roman Emperors later on had to wage what were essentially campaigns of conquest in Northern Italy in order to get crowned by the Pope – and then hurry back to Germany to fight inevitable coalition of rebel dukes which will have appeared by then.

Alaric besieged Rome three times in early 5^th century because he wanted to be recognized as magister militum by the Emperor there. While Emperor himself was basically powerless militarily by this time, legitimacy and authority gained by long rule of Rome in the West meant that barbarian leaders only had true royal legitimacy if the Roman Emperor recognized them. Visigoths eventually sacked Rome in 410 AD, but this was not the original goal.

Combined Motives

Of course, leaders and states may have more than one motive to start a war. Natural disaster may have led to scarcity of resources. Or perhaps scarcity of resources had made people living in an area warlike, and something happened – a disaster, an ambitious ruler or a new belief system – that made them turn their energies into outward conquest instead of previously typical internal squabbles. Alternatively, historical animosity may be what pushes two states into war over scarce resources, geography or different belief system. Whatever the case, combining motives will help wars feel more realistic, deeper and more immersive.

Conclusions

Wars in fantasy may erupt for any one or multiple of above reasons. But regardless of if it is a Dark Lord attempting to create a utopia by force, or a bunch of enterpreneurs doing business, nobody fights a war for no reason. And the reason behind the war will shape the way war is being fought. This will allow the author to create a compelling and immersive story that will keep readers engaged. Motives of war will also determine the conduct of war as well – an attacker whose motive is merely plunder will come, raid, rape, pillage and plunder, and leave. Attacker whose motive is conquest however will stay to try and besiege towns, resorting to raiding only if outright conquest is not possible (Mongols and Ottomans both did this).