The Hundred Years’ War Revisited: The Medieval ‘World War’

By Andrew Latham and Rand Lee Brown II

As we discussed in our last column, the “Caroline War” started out as just another phase in that clash between the kingdoms of England and France that we have all agreed to mislabel the Hundred Years’ War. Very quickly, however, it would metastasize into something quite different: a kind of world war involving nearly every major power in Latin Christendom. To be sure, other realms had been involved diplomatically and militarily in this essentially Anglo-French war from the very beginning of the conflict. But the Caroline War witnessed the deliberate extension of combat operations to these realms, creating new combatant “theatres of operations.”

In these new combatant theatres, the French and English pursued their respective geopolitical agendas not only directly, but through allies and proxies who, though generally supportive of the goals of their “superpower” patrons, also had interests and objectives that were not always perfectly aligned with those of their respective patrons.  Given this geopolitical reality, it is perhaps not too surprising to find that victory in this phase of the war tended to go those who could triumph not only on the field of arms, but on the field of diplomacy as well; for the ability to wrangle one’s allies and proxies in the service of one’s cause was absolutely necessary if one was to concentrate all the various arrows in one’s strategic quiver at a single decisive point.  Significantly for the course of both the Caroline War and the longer conflict of which it was a part, if the former sometimes favoured the English king, the latter almost always favoured the king of France, as it was Charles V who revealed himself to be the more adept of the two sovereigns at what we would now call grand strategy.


One of the first theatres to be added to the new strategic map was that of the small Pyrenean Kingdom of Navarre, ruled then by the notorious Frenchman (and son of a cadet branch of the Capetian French Royal family) Charles II. “Charles the Bad” as he was known was an important English ally for two reasons. First, his military support secured the strategically crucial English southern flank in Gascony.  Second, and at least as importantly, Charles – via his claims to lands within the kingdom of France (especially Normandy) – put immense political pressure on the French kings.  Although renowned for his duplicitous power politics, and his notorious inconstancy, by 1360 Charles of Navarre had become a major strategic and political burr under the saddle of the Valois king and his allies and a major bastion of England’s continental empire.

Battle of Cocherel, depicted in the later 14th century. British Library, Yates Thompson 35 f. 71.

Following Charles’ defeat at the hands of Bertrand du Guesclin at Cocherel in 1364, however, the strategic tide began to turn, first for Charles and then for his sometime English allies. To begin with, his strategic position having been seriously compromised, Charles was forced to spend the next decade trying to regain his footing by adopting a more political strategy – one focused less on hitching his horse to a hoped-for and vanishingly unlikely decisive English military victory and more on pursuing his his own political war-of-position to seize the French crown through cunning and guile.


Perhaps predictably, though, the combination of the French king’s political savvy, the English king’s geopolitical blunders, and Charles own inconstancy and ineptitude ultimately brought his house of cards crashing down about him. Sandwiched on the one hand between hostile Valois loyalists in France and French-allied Castile on the other, and abandoned by a thoroughly alienated England increasingly disaffected by the Navarrese sovereign’s faithlessness and incompetence, Charles’ kingdom was humiliated and neutralized as a geopolitical force. As if to punctuate this demise in Navarre’s fortunes, Charles himself would die a famously gruesome death (being accidentally burned alive during a medical procedure) in 1387.

The Low Countries

The independent city-states of Flanders also participated substantially in the war during this time. While the Flemish textile economy had been a major factor in the war from its start, the desire for Flemish independence was a useful geopolitical tool with which Edward III could threaten the French northern border. Charles V, recognizing Flemish independence as the dire threat that it was, directed much of his energies there first after becoming King. Again, English support for their allies flagged seriously at a crucial moment; Edward provided little support for the anti-French principalities and what aid he did manage to make available was mediocre at best. Confronted with this discouraging reality, many states in Flanders simply changed horses and submitted to French rule.

Others, like fiercely independent Ghent, continued to resist as best they could while vainly hoping for more meaningful assistance from their increasingly unreliable English allies. Edward didn’t grasp the seriousness of the situation until the French annihilated the last major independent Flemish army at Roosebeke in 1382. As if to add insult to injury, the English attempted to salvage the situation by launching the bizarre and ultimately abortive “crusade” led by Bishop Despenser of Norwich that achieved little more than the devastation of a few dozen square miles of Flemish coastal territory. The net result: Flanders slipped back into France’s geopolitical orbit, never to escape it again.

Map of France in 1382, showing English conquests in pink and Flanders (top) in yellow – from The Public Schools Historical Atlas edited by C. Colbeck, 1905.

The Iberian Peninsula

Arguably the most significant of the new combatant theatres to emerge during this phase of the seemingly interminable Anglo-French war, however, was that of the Iberian Peninsula. The great kingdom of Castile found itself in the midst of a fierce civil war after the sudden death of Alfonso XI from the Black Death in 1350. On one side were the partisans of Alfonso’s legitimate heir, Pedro – an infamously vicious character known to posterity as “the Cruel,” and on the other, the forces of Alfonso’s illegitimate son Enrique de Trastamara. Both reached out to England and France respectively for support, pledging economic and political support in return.


Pedro finally won the exclusive backing of Edward the Black Prince, who invaded Castile in 1366, obliterating the Franco-Spanish forces of Enrique at the Battle of Najera. However, Pedro predictably failed to honor his promises to the Black Prince, who was forced to retreat back into Aquitaine, utterly bankrupt and disgusted by his faithless ally’s duplicity and sadism.  Enrique rebounded from this defeat and eventually murdered Pedro, tipping the balance of power in Castile decisively in France’s favor.

Despite all these strategic setbacks, the English did experience some notable geopolitical successes in one part of the Iberian theatre, and that was in the nascent kingdom of Portugal. During this time, the Portuguese had been ferociously defending their independence from a voracious and ever-encroaching Castile. Once Castile fell to the French-backed Enrique de Trastamara, the English recognized the geopolitical value of supporting Portuguese independence efforts and dispatched substantial military support in the form of small contract armies and military advisors.

These efforts came to fruition at the Battle of Aljubarrota in 1385 where a massively outnumbered Anglo-Portuguese force decisively defeated a Franco-Castilian invasion army, securing Portuguese independence for King João I and, in 1386, produced the Treaty of Windsor between England and Portugal – a treaty of alliance that has remained in effect to this very day.


Further Reading:

Curry, Anne, Essential Histories: The Hundred Years War, 1337-1453 (Osprey Publishing, 2002)

Dr. Andrew Latham is a professor of political science at Macalester College in Saint Paul, Minnesota. He is the author, most recently, of a monograph entitled Medieval Sovereignty, to be published in 2020 by ARC Humanities Press.  You can visit Andrew’s website at or follow Andrew on Twitter @aalatham

Capt Rand Lee Brown II is a commissioned officer in the United States Marine Corps currently assigned to Marine Forces Reserve.  Holding a Master of Arts degree in Military History from Norwich University with a focus on medieval warfare, Capt Brown has written on military history for a variety of forums, including the Marine Corps Gazette and

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Top Image: Europe in the 14th century – The Public Schools Historical Atlas by Charles Colbeck (Longmans, Green, 1905)