Military Innovations of the Hundred Years' War

The Hundred Years’ War witnessed a profound transformation in European military technology, organisation, and tactics. Three structural shifts are visible in the war’s record. The first was the rise of the English longbow to dominance as an infantry weapon. The second was the development of the chevauchée as a deliberate strategic instrument, and the parallel rise of the strategy of avoidance as a response to it. The third was the integration of gunpowder artillery into the field army, culminating in the Bureau brothers’ French train and the decisive use of artillery at Castillon. The war also saw important changes in military organisation: the decline of the feudal levy, the rise of paid professional armies (the English indents and the French compagnies d’ordonnance), and the development of a new art of fortification.

The most useful single treatment is Clifford Rogers’ War Cruel and Sharp (2014) and his The Oxford Encyclopedia of Medieval Warfare and Military Technology (2010). The standard French treatment is Contamine’s La Guerre de Cent Ans (1968), particularly the chapters on military organisation. The older work of Henri Contamine, Guerre, État et société à la fin du Moyen Âge (1972), is the classic study of the late-medieval fiscal-military state.

The English longbow

The most famous military innovation of the war was the English longbow, a tall bow made of yew wood, capable of firing arrows with much greater force and at a much faster rate than the crossbow, the principal alternative weapon of the age. A skilled longbowman could fire perhaps six arrows in the time it took a crossbowman to fire one, and the longbow was far more accurate at long range. The longbow was first used to devastating effect at Crécy (1346) and remained the dominant English battlefield weapon until the gunpowder cannon of the 15th century displaced it.

The longbow required years of training to use effectively. English kings, recognising the importance of the weapon, had long required that all able-bodied men practise at the butts, and the longbow was a national weapon in a way that no other weapon of the age was. The Assize of Arms of 1252 and the Statute of Winchester of 1285 had set out the requirement; the Edwardian and Lancastrian war effort was the first to be based on the assumption that the requirement was real. The result was that the English could put into the field large numbers of skilled longbowmen, and the longbow became the foundation of English military success in the Edwardian phase.

The longbow was decisive at Crécy, Poitiers, and Agincourt. It was less decisive at the battles where the English did not control the ground, and it was eventually displaced by the gunpowder cannon in the 15th century. The displacement was, however, slower than the older literature suggested: longbowmen were present in English armies into the 16th century, and the crossbow was a continuous presence in French and Italian armies throughout the period.

The chevauchée

The chevauchée was a strategic system based on the systematic devastation of the enemy’s territory. In its mature form, the chevauchée was not a random raid but a carefully planned campaign of destruction, designed to force the enemy to give battle, to demonstrate the inability of the enemy’s government to protect its subjects, and to gather plunder to pay for the war.

The English used the chevauchée extensively in the Edwardian phase. The most famous chevauchée was Edward III’s campaign of 1346, which culminated in the Battle of Crécy. The strategy, however, was not uniquely English: the French under du Guesclin used a modified version of the strategy in the Caroline phase, deliberately avoiding pitched battles and using a scorched-earth policy to neutralise English chevauchées. The strategy of avoidance, the standard French response to the chevauchée, was a strategic innovation in its own right.

The chevauchée is one of the canonical elements of medieval strategy, and the standard treatment is the work of Rogers in War Cruel and Sharp (2014). The chevauchée is treated in detail in its own long-tail article; the related phenomenon of ravaging is treated separately.

Plate armour

The war also saw the development of plate armour, the full-body metal armour that became the standard equipment of the medieval knight in the late 14th and 15th centuries. The plate armour of the late Middle Ages was a sophisticated technological achievement, made of carefully shaped and articulated metal plates that could deflect arrows and swords. The development of plate armour was, in part, a response to the longbow: the mail armour of the early 14th century was no protection against the heavy arrows of the longbow, and the development of plate armour was intended to provide better protection. The plate armour of the late 14th century, however, was not without its weaknesses: it was heavy, it was hot, and it could still be penetrated by the longbow at close range.

Plate armour reached its technical peak in the late 15th century, with the white harness of the Italian and German workshops, and the famous engravings of the Maximilian armour of c. 1500. The development of gunpowder artillery, however, made even the best plate armour obsolete within a generation.

The decline of the feudal levy

One of the most important military innovations of the war was the decline of the feudal levy and the rise of paid professional armies. The old feudal system, in which each vassal was bound to provide a certain number of knights for a fixed period of service, had been breaking down for some time before 1337, but the war accelerated the process.

The English response was the indent system: the king contracted with experienced captains to raise paid companies of archers and men-at-arms for the duration of a campaign. The system emerged in the 1370s and was dominant by the 1420s. The French response, slower, was the compagnies d’ordonnance of Charles VII (1445), the first permanent professional field army in Western Europe, organised in 15 companies of 100 lances each. By the end of the war, both kingdoms had moved decisively away from the feudal model of military service and toward a system of paid, professional armies financed by royal taxation.

The introduction of gunpowder

Perhaps the most important military innovation of the war was the introduction of gunpowder artillery. Gunpowder had been invented in China and had been used in warfare in Europe since the early 14th century, but it was only in the late 14th century that the weapon began to be used on a significant scale in European warfare. The French were the first to develop a substantial train of artillery, and the French victory at the Battle of Castillon in 1453 demonstrated the power of the new weapon.

The French development of artillery was the work of the Bureau brothers, Jean and Gaspard. Jean Bureau (c. 1390–1463) was the principal architect of the French train, and his work on metallurgy, gunpowder composition, and field-tactics had produced a train that was, by 1450, the most powerful in Europe. The French train was a major factor in the reconquest of Normandy and Gascony, and Castillon is conventionally cited as the moment when the gunpowder cannon definitively replaced the longbow as the dominant battlefield arm.

The integration of gunpowder into the field army was a slow process. The first cannon, in the early 14th century, were large, heavy, and slow-firing, useful mainly for siege warfare. The development of smaller, faster-firing pieces in the 15th century, and the development of the field carriage and the field fortification, allowed the cannon to be used as a mobile battlefield weapon. Castillon is conventionally cited as the moment when the integration was complete, but the standard reading, set out by the contributors to Rogers’ Oxford Encyclopedia (2010), is that the integration was the work of the entire 15th century.

The tactics of the war

The English tactical system, developed in the Edwardian phase and refined through the Lancastrian phase, combined the longbow with the dismounted man-at-arms. The English would take up a strong defensive position, deploy their longbowmen in front of their men-at-arms, and invite the enemy to attack. The enemy, charging into a hail of longbow arrows, would be devastated before they could reach the English lines.

The French, who had been defeated by this system at Crécy, Poitiers, and Agincourt, eventually developed a counter-tactic. The French would avoid battle where possible, and when battle was unavoidable, they would use a combination of dismounted men-at-arms, crossbowmen, and (eventually) artillery to neutralise the English longbow. The French victory at Castillon was the result of this new system.

The legacy

The military innovations of the Hundred Years’ War had a profound and lasting impact on European warfare. The longbow, which had been the dominant infantry weapon of the age, was eventually replaced by the gun. The mounted knight, who had been the dominant arm of medieval armies, was eventually replaced by infantry. The paid professional army, which had been developed during the war, became the model for European armies in the following centuries. The gunpowder artillery train, which had been developed by the French during the war, became the model for European artillery in the Renaissance.

The standard military reading, set out by Rogers, is that the Hundred Years’ War is the central case study of the medieval “military revolution.” The structural reading, set out in the work of the contributors to Rogers’ Oxford Encyclopedia and developed in the more general work of Geoffrey Parker (The Military Revolution, 1988), is that the war was both cause and consequence of the transition from medieval to early modern warfare.