Battle of Agincourt vs Hundred Years' War: Lancastrian Phase (1415–1453)

The battle showcases the bankruptcy of French feudal dogma and the triumph of late medieval English asymmetric adaptation. Henry implemented a static annihilation doctrine using a combined-arms force of archers and infantry, exploiting the terrain. The French, inflexible to the changing conditions, persisted in uncoordinated, piecemeal frontal charges, scripting their own catastrophe.

The English successfully applied their longbow and mounted infantry doctrine, but it rigidified and failed to adapt to the artillery age. The French showed high flexibility by abandoning the feudal cavalry tradition and transitioning to an artillery-centric siege doctrine and standing army. Castillon proved the French had embraced asymmetric innovation by constructing fortified artillery positions in the field.

Battle of Annihilation

Challenge and Siege — The war consisted of a series of campaigns shaped by dynastic claims, involving pitched battles (Agincourt, Verneuil) and sieges of castles; the aim was territorial control and political allegiance rather than annihilation. The English initially employed attrition and shock tactics, while the French responded with strategic siege artillery.

King Henry V correctly identified his center of gravity (Schwerpunkt) as the disciplined armored infantry, supported by enfilading fire from the archer wings, and concentrated this force in the narrow defile. The French erroneously placed their center of gravity in the heavy cavalry; when this force was neutralized, the remaining dismounted knights failed to form any coordinated mass of effort.

The English defined their Schwerpunkt as destroying the main enemy army in field battle and gaining influence over political centers (Paris, Reims); however, this focus dissipated as French resistance adopted guerrilla-like tactics. The French centered their resistance on the Bourges and Loire line, concentrating artillery and professional army there to gradually push the English back. Burgundy's defection allowed the French to shift their Schwerpunkt to the northeast.

Henry V employed a simple but effective deception by enforcing total silence during the night and concealing his archers behind pre-positioned stakes. His tactical maneuver to angle his army to force the French into the narrowing terrain was a strategic trap; additionally, the threat of a raid on the French baggage train during the battle served as a distraction.

The English employed strategic deception by fueling the French civil war and drawing Burgundy to their side, dividing the enemy through diplomatic maneuvers. The French used psychological deception through Joan of Arc's 'holy mission' propaganda and may have used tactical ruses like camouflage or feigned retreats at Castillon. Overall, both sides used intelligence for deception, but French popular support provided more opportunities for ruses.

The English shock effect came not from cavalry or artillery, but from massed archery delivering tens of thousands of arrows per minute. This arrow storm fatally wounded horses in the French vanguard, breaking the cavalry charge with sheer impact, and subjected the dismounted men-at-arms to a relentless rain of death as they slogged through the mud, halting their advance.

English longbows created physical and psychological shock by decimating the enemy at range in battles like Agincourt and Verneuil, reinforced by mounted archers. The French, in the war's final stage, innovatively used field artillery to shatter English lines; at Castillon, artillery fire completely halted the English advance. Both sides attempted to synchronize shock weapons with maneuver, but the French gained a long-term edge through technological innovation.

At Agincourt, 'heaven' and 'earth' were England's greatest allies. The heavy rains and soft, clay-like soil pinned down the heavily armored French knights, slowing their movement to a crawl. The narrow terrain, flanked by woods, prevented any French envelopment, offering the English archers an ideal killing ground.

At Agincourt, heavy rain bogged down the heavily armored French cavalry in mud, greatly benefiting English archers. Generally, France's river networks and forested terrain favored defense, while the English depended on coastal bases for logistics. At Castillon, the French used high ground to establish fortified artillery positions, leveraging terrain to their advantage.

Despite the French knowing the English were exhausted, they failed to analyze Henry's determination and positional superiority, a fatal intelligence gap. Conversely, Henry correctly assessed the French command structure's impatience and feudal rivalries, successfully provoking them into attacking under the worst possible conditions.

The English initially analyzed French court divisions and enemy weaknesses well; Henry V's campaign planning relied on this intelligence. Over time, however, the French gained intelligence superiority through local support and guides on their own terrain. Even Joan of Arc's claim of 'divine messages' acted as a form of intelligence advantage, boosting French morale while unsettling the English.

Henry V's deployment of his heavy infantry behind archer lines and his acceptance of battle by forcing the French to attack was a masterclass in central position advantage. The French advance, compressed into a single, muddy axis and lacking coordination, allowed the English to use their interior lines to repulse each wave piecemeal; it was positional warfare, not speed of maneuver, that proved decisive.

The English demonstrated rapid maneuver capability at the start of campaigns through disciplined marching order and mounted troops; however, their supply lines became dangerously extended as they penetrated deeper into France. The French successfully used interior lines to shift forces to threatened areas. Late-war mobility of French artillery units accelerated siege operations.

The English army, cut off, exhausted, and far from home, was united by a 'victory or death' ethos, cemented by King Henry V's charismatic leadership and the Saint Crispin's Day speech. The overconfidence of the French, bred from numerical superiority, and the bitter rivalries among the nobility, however, meant they lacked a collective fighting spirit, which collapsed entirely upon the first arrow volleys.

Henry V's victory at Agincourt instilled an 'invincibility' psychology in the English army, but this morale eroded after Bedford's death and growing French resistance. In contrast, Joan of Arc's emergence infused the French with a sense of divine legitimacy and belief in victory, reversing the 'friction' against the English. The coronation of Charles VII cemented a lasting morale advantage through national unity.

The English, prior to battle, exploited the Burgundian-Armagnac civil strife to divide the enemy, and their relentless stance at the Siege of Harfleur created a psychological shock. However, the true victory without fighting materialized on the battlefield as French panic and indiscipline cost them their morale advantage, leading to a collapse without a concerted fight.

England succeeded in weakening the enemy without battle by allying with Burgundy and fueling the French civil war; however, this was temporary. France ultimately applied 'victory without fighting' more effectively by diplomatically isolating England through the Treaty of Arras (1435), which brought Burgundy back to its side. Long-term, French diplomacy and reconciliation strategy detached English allies.