Why battles could be so decisive in the Middle Ages

By Georgios Theotokis

I just wrote a book about the Middle Ages viewed through the lens of the most potent and dramatic aspect of war – battle. Its central aim is to stimulate the reader’s interest on the importance of pitched battles in war, and to explain the geo-political gravity of twenty of them in shaping the European continent. 

One issue that has been brought up by historians in recent decades is the definition of military history. This is a branch of history that focuses on the core element of war, the battle itself – on military tactics, strategies, armament and the conduct of military operations – what we may call “battle narratives”. But in the last two generations, military history has grown up to be much more than a look into the “art” or “science” of war. According to the, so-called, ‘New Military History’, a military historian should focus on three main contexts; first, the political-institutional context that covers the relation between the political and the military institutions within a state and to what degree an army could be used as an instrument of politics. Then, there is the socio-economic context, an area that includes the impact of war on societies (economic productivity, logistics, recruitment, technology etc.) and that of societies on war, and, finally, the cultural context that shows the interaction of warrior values with the cultural values of societies in general (glorification or condemnation of warrior values through epic poems, folk songs and tales etc.).


Nevertheless, this book deviates from the “fashionable” narratives of the, so-called, ‘New Military History’ that have dominated the historical output since the 1980s, although that does not mean that I am disputing or dismissing the importance of matters such as administration, the institutional framework for warfare, supply systems and logistics, the society during war, and the importance of sieges, raids, skirmishes and ambushes to warfare during the Middle Ages.

Rather, the emphasis on this study is both on analysis and narratives, and each chapter considers and evaluates campaigns and battles that demonstrate classic and sometimes unchanging aspects of the “Art of War,” as well as illustrating changes in tactics and practices that came as a response to new challenges, weapons, and environments. Therefore, it is my aim to reintegrate the operational, tactical, technical and equipment aspects of the conduct of warfare, and to give to the general audience a wider understanding of how significant and decisive pitched battles could be on a macro-historical analysis which seeks out large, long-term trends in world history.


Death of Harold Godwinson in the Battle of Hastings
Death of Harold Godwinson in the Battle of Hastings

The concept of decisive battle

Despite the fact that they have fallen in disfavour in the last twenty or thirty years, to the point that it has become ‘unfashionable’ to ascribe global or even regional geo-political developments to their outcome, yet battles have traditionally attracted great attention from scholars because they have demonstrated to have the potential to exert an enormous impact on the course of history.

But what is it that makes a battle decisive? The answer is straightforward: impact! A decisive battle should have long-term socio-political implications between adversaries and profoundly affect the balance of power on more than just the local level. But it is a specific characteristic of (decisive) battles that makes them invaluable for historians to study, their rarity. And the reason behind this can easily be deduced from the sources:

‘It is preferable to subdue an enemy by famine, raids and terror, than in battle where fortune [‘fortuna’] tends to have more influence than bravery.’ [Vegetius, Epitome of Military Science, c. 400]

‘To try simply to overpower the enemy in the open, hand to hand and face to face, even though you might appear to win, is an enterprise which is very risky [‘της τυχούσης’] and can result in serious harm. Apart from extreme emergency, it is ridiculous to try to gain victory which is too costly and brings only empty glory.’ [Emperor Maurice’s Strategikon, c. 600]


‘It is good if your enemies are harmed either by deception or raids, or by famine; and continue to harass them more and more, but do not challenge them in open war, because luck [‘της τύχης’] plays as a major role as valour in battle.’ [Emperor Leo VI’s Taktika, c. 900]

Therefore, the rarity of battles in the pre-industrial era comes as a direct result of a hugely influential factor: chance! Although the outcome of a battle does not necessarily prove the social, economic or technological superiority of a ‘military culture’ over another, other things like an accidental arrow, unexpected rainfall, fog or a royal horse running astray in the battlefield could upset the turn of events. Bearing in mind that the Middle Ages were a period in history when a king or an emir were at the forefront of fighting, and their units often bore the brunt of an enemy attack,  the death of a leader or extensive losses in the battlefield could dramatically upset the balance of power between two forces for many years or even decades – or even forever. And even if the sources of a polity’s material and cultural wealth were not directly harmed by the battle, it could take years to reorganize armies, rebuild morale and international alliances, and train and equip new combatants.

15th-century French miniature depicting the Battle of Manzikert – BNF MS Français 226 fol. 256

To give a characteristic example: every medieval history enthusiast has heard of the famous story (historically accurate or not, I provide an answer in the corresponding chapter on the Battle of Hastings) of King Harold dying in the field of battle at Hastings by an arrow through his eye. The king’s untimely death proved to be the catalyst that tipped the scale in favour of the Normans and changed the face of English history for ever. At the Battle of Dyrrhachium, some fifteen years later (1081), another Norman invader – Robert ‘Guiscard’ Hauteville – also defeated the Byzantine Emperor’s armies in modern Albania. But even though his Norman knights had the emperor Alexius Comnenus surrounded after he fled the battlefield, the emperor managed to escape and establish a rallying point at Thessaloniki. His death would have brought the state into the brink of a renewed civil war, just like the aftermath of the Battle of Manzikert had done ten years before (1071), and the future of the Byzantine Empire would have been very different.


Therefore, I firmly believe that, regardless of whether battles are trustworthy or untrustworthy assessments of historical entities and movements, they are rare events and they form the ultimate “Darwinian test” for two sides facing each other in a frenzied and violent interaction that would provide history with a winner. They are the catalyst that introduces an element of chaos in history, where small inputs can create very large perturbations. And for that reason, I find John Keegan’s assertion to be fitting as a concluding remark on the importance of battles in world history: ‘For it is not through what armies are but by what they do that the lives of nations and of individuals are changed.’

The battles that shaped medieval Europe

In an effort to study the history of Medieval Europe in a more effective way, historians have divided these twelve centuries we have come to know as the ‘Middle Ages’, from the middle of the fourth to the middle of the fifteenth, into periods of study. Periodization, therefore, has become an inescapable part of the study of history at all levels. Military historians have not escaped this process of slicing up the past into pieces of varying sizes, and then allocate special names, or ‘labels’, that would help them to demarcate each slice as something unique.

As the impact of the migration of nomadic and semi-nomadic nations into the European landmass shaped the continent in a profound way between AD 400 and 1100, in what we will come to know as ‘The Age of Migration and Invasion,’ the victory of Flavius Aetius, at the Battle of the Catalaunian Fields, in 451, not only stopped Attila from succeeding in establishing a kingdom in Gaul, but it also allowed for Visigoth, Frankish and Burgundian hegemony in Gaul to flourish. It would be these ‘new’ military forces of the Germanic ‘successor’ kingdoms, which reflected the fusion of Roman and barbarian elements that characterized the whole society after the 5th century, that would clash at the decisive Battle of Vouillé, in 507, when the emerging power of the Salian Franks under King Clovis crushed the Visigoths of France and Spain, and settled once and for all the future of continental Gaul. Vouillé would form the terminus of a long process that had begun with emperor Theodosius’ victory at the Battle of Frigidus in 394, after which the eastern Roman emperor not only asserted control over the western parts of the empire after the slaughtering of the western army, but we see the beginning of the process by which large parts of Gaul and the Rhine frontier were left on their own, in a form of a political limbo, while the Roman empire was contracting closer to the Mediterranean Sea.

Further invasions of Europe in the ninth and tenth centuries came from three directions—the north, the east, and the south—and their impact was considerable. Muslim pirates that plagued the southern coasts of Europe were but a distant echo of the disciplined Umayyad armies that had poured out of the Arabian Peninsula in the seventh century. At the Battle of Guadalete, in July 711, the Visigothic kingdom was eclipsed by the armies of the Arabs from Morocco, an event that radically changed the course of the history of Spain and Europe for the next five centuries, giving rise to the ideas of Christian Holy War. It would take the strategic brilliance of Charles Martel to defeat the, ever expanding, emirate of Al-Andalus at the Battle of Tours, in 732, a victory which secured Charles’ position as the most powerful man in France. Prior to that decisive victory in central France, the Umayyad army and navy was also decisively defeated in the outskirts of the Byzantine capital, following the unsuccessful Second Siege of Constantinople between the summer of 717-18. The Byzantine capital’s survival preserved the Empire as a bulwark against Islamic expansion into Europe well into the fifteenth century and the coming of the Ottoman Turks.

The Battle of Lechfeld, also known as the River Lech, from a 1457 illustration in Sigmund Meisterlin’s codex of Nuremberg history

Emerging in the footsteps of Attila the Hun, the Magyars began to trouble the eastern borders of Europe in the middle of the ninth century. Their massive raids cut deep swathes of destruction through central and southern Europe for more than thirty years (900-930), defeating no fewer than three large German armies between 907 and 910. Therefore, the significance of the German victory on the banks of the River Lech, in 955, was paramount for the future and stability of the Holy Roman Empire, a victory that put a check on the Magyar raids, while also opening the way to their eventual Christianization.

The Norman establishment in Italy is also particularly interesting because, by the middle of the eleventh century, they had become the undisputed masters of the entire southern Italian provinces of Apulia and Calabria, owing to their decisive victory at the Battle of Civitate, in 1053, where they solidified their political and military dominance in the South. Thirteen years later, William Duke of Normandy would also make his bid for the English throne in 1066, in the most remarkable and well-planned of all enterprises conducted by a Norman leader in history, the climax of which was William’s triumph at the Battle of Hastings in October.

Battle of Bouvines in Bibliothèque Nationale de France MS Français 2813 fol. 253 v

The period between AD 1100 and 1500 has been described as the ‘Age of Traditions in Conflict’, an age of political instability and expansion in the periphery of Europe (the Middle East, Livonia, Spain, Italy and Sicily), but also an age of social renewal in western Europe, which gave rise, in the century between 950 and 1050, to a new aristocratic social order and a new socio-military system. In the eleventh, twelfth, and thirteenth centuries, while the Holy Roman Empire and the Papacy were engaged in prolonged conflict from which neither would emerge fully victorious, England and France evolved into centralised states. The transformation from a ‘sacred’ into a bureaucratic monarchy was one of the most fundamental historical developments of the Late Middle Ages, and had a profound impact in the way war was waged between AD 1200 and AD 1400. As the Capetian Kings of France developed a state policy of expanding the royal demesne and tightening the royal lordship over the major dukes and counts of France in the twelfth century, it would bring them into direct conflict with the over-extended Angevin empire. It would be Philip Augustus’s greatest achievement, the destruction of the Angevin empire, as the crushing blow eventually came at the Battle of Bouvines, in 1214. The outcome of the battle dramatically changed the political face of Europe, turning Philip into the strongest monarch in Europe, while plunging England into a political and financial crisis that would force King John to sign the Magna Carta in 1215.

In an age of expansion into Europe’s periphery, the idea of Holy War brought Christian knights into conflict in theatres of war far removed from the Middle East and the Holy Land. The expulsion of the Muslims from Iberia – the so-called Reconquista – would last for over four centuries, and it certainly looked like a wild dream after the humiliating defeat of King Alfonso VIII of Castile at the Battle of Alarcos (19 July 1195). Nevertheless, the Battle of Las Navas de Tolosa, in 1212, allowed for the Christian kings of Spain to reclaim the military initiative and the opportunity to recover the disputed lands between the Rivers Tagus and Guadalquivir.

While Crusader expansion seemed to pick up pace in Iberia, it was dealt a crushing blow in the Baltic region. There, the political and territorial ambitions of the Teutonic Knights, and of the Swedish and Danish Kings clashed with the growing influence of Russian-Orthodox Novgorod. The outcome of the Battle of the Lake Peipus, in 1242, put a long-term halt on the eastward expansion of the Crusaders in the Baltic region, and it drew a distinctive geo-political line between the forces of Russia and those of Sweden, Denmark and Prussia. The decisive blow to the very existence of the Order would be delivered about a century and a half later, when the victory of the allied Lithuanian-Polish armies at the Battle of Tannenberg, in 1410, would irreversibly re-shape the face of eastern Europe within half a century after the battle. The Crusader movement was dealt another massive blow in the southern Balkans. Following the divergence of the Fourth Crusade to Constantinople and the humiliating conquest of the Byzantine capital by the ‘Christian’ armies of Latin Europe in 1204, it would be the empire of Nicaea, in western Asia Minor, that would defeat the combined armies of the Despotate of Epirus, Sicily and the Principality of Achaea at the Battle of Pelagonia, in 1259. It was a decisive event in the history of the Eastern Mediterranean that ensured the Byzantine reconquest of Constantinople and the end of the Latin Empire in 1261.

Battle of Tagliacozzo in a 14th century manuscript

The Battle of Tagliacozzo, in 1268, is interesting for military historians from both a political and military perspective. On the one hand, the outcome of the battle underlines the difficulties that a heavily armed mounted force had to overcome when operating in tight formations in a relatively broken, hilly or marshy terrain, which was dominated by a river or an uphill castle. Order and discipline were paramount for a cavalry force, especially when it was re-grouping after an unsuccessful charge, hence the great tactical significance of the feigned flight manoeuvre that saved the day for the Sicilian King, Charles of Anjou. But Tagliacozzo should also be remembered for its political ramifications for the future of Italy and Sicily, as it irreversibly broke the centuries-old political connection between Germany and the Kingdom of Sicily through the Hohenstaufen.

Then, we come to the Battle of Sempach, in 1386, which should be viewed not only for decisively tipping the balance of power west of the Rhine in favour of the Swiss Confederation, that would eventually lead to the establishment of the state of Switzerland. Sempach should also be appreciated as the climactic victory in a period when independent and rich cities and states in northern Italy, Switzerland and Flanders were capable of putting large battle-worthy infantry armies in the field against the aristocratic knightly armies of the Middle Ages, and crush them!

The Late Middle Ages (AD 1100–1500) was an age of global contact between different ‘military cultures’ through war and trade, and it was dominated by the Mongol explosion of the thirteenth century at the eastern end of the Mediterranean. The Crusades also brought western Europe, Byzantium, and the Muslim world, with its connections to Central Asia’s nomads, into an extended period of competition and exchange. The Crusades, therefore, represent the culmination of this trans-cultural contact, connecting war and religion in a mixture that would be responsible for some of the worst massacres in history. The eventual fall of Byzantium in the hands of the Ottoman Turks would signal the end of an era, and would demonstrate that such trans-cultural contact could lead to a ‘fight to the death’.

The defeat of the Crusade of Nicopolis on the outskirts of the Danube city, in 1396, had a devastating effect on European morale, allowing the Ottomans crucial time to consolidate and expand their territories in the Balkans, while they were allowed to recover from the setback of the Mongol invasion in AD 1402. However, it was the repercussions from the Christian defeats at Varna, in 1444, followed by the rout of the Crusader army at the Second Battle of Kosovo, on 20 October 1448, that were ground-breaking for the future of Europe. They sealed the fate of both the Balkans and the Byzantine Empire, while giving a great boost to the Ottoman prestige in the Muslim world as conquerors and fighters for the Jihad. Their ultimate spoil would be Constantinople, five years later!

Georgios Theotokis’ book, Twenty Battles that Shaped Medieval Europe, is now available. Click here to visit the publisher’s website or buy this book on

Georgios Theotokis: Ph.D History (2010, University of Glasgow), specializes in the military history of eastern Mediterranean in Late Antiquity and the Middle Ages. He has published numerous articles and books on the history of conflict and warfare in Europe and the Mediterranean in the Medieval and early Modern periods. His latest book is Twenty Battles That Shaped Medieval Europe. He has taught in Turkish and Greek Universities; he is currently a postdoctoral researcher at the Byzantine Studies Research Centre, Bosphorus University, Istanbul. Click here to read more from Georgios Theotokis.

Top Image: British Library MS Royal 20 C VII   fol. 34