Why Was Agincourt a Disaster for France?

Agincourt, fought on 25 October 1415, was the worst military disaster in French history between Poitiers (1356) and the late 18th century. The English army, perhaps 6,000 strong, destroyed a French army of between 12,000 and 18,000 men, killed a substantial proportion of the higher French nobility, and opened the way to the conquest of Normandy and the Treaty of Troyes. The reasons for the disaster were, in roughly equal measure, a tactical choice made on the field of battle and a strategic decision taken at the council table.

The strategic decision to fight

Henry V invaded Normandy in August 1415, took Harfleur after a five-week siege, and marched his reduced army overland to Calais. The French had three months to choose their response. The decision, taken by the council of Charles VI in September 1415, was to assemble a major army, block Henry’s route, and force him to fight. The strategic reasoning was sound in principle: a chevauchée from Harfleur to Calais was a long and exposed march, and the English were weakened by dysentery, by the garrison left at Harfleur, and by the loss of men in the siege. The strategic reasoning was unsound in execution. The army that assembled was too large to be effectively commanded, too slow to bring the English to battle on ground of French choosing, and too politically divided to act as a single force.

The field of battle

The battle was fought on a strip of open ground between the forests of Agincourt and Tramecourt, in Picardy, a few miles east of the modern town of Hesdin. The ground narrowed the French front and forced the attackers into successive columns. The English army, deployed on a slight rise, was a fraction of the size of the French. The English, as at Crécy, dismounted their men-at-arms and placed them in a single line flanked by wedges of longbowmen, with sharpened stakes at their feet. The French, having marched all night and spent the morning in formation, were tired and hungry by the time the advance began.

The longbow

The English longbow, a yew bow of 6 to 7 feet drawn to the ear and fired at a rate of six to twelve arrows per minute, broke the first French line — the Genoese crossbowmen — by direct fire. The Genoese bowstrings had been wetted by the previous night’s rain, and the longbow’s faster rate of fire and longer range told. The first line of French men-at-arms, led by the constable Charles d’Albret, then advanced on foot, became entangled with the retreating Genoese, and was broken by a second volley of arrows and the English counter-charge. The second French line, containing the Duke of Alençon, advanced and was broken in turn. The third line, the Orléans contingent, never properly engaged.

The standard English treatment of the longbow is Clifford Rogers’ War Cruel and Sharp: English Strategy under Edward III, 1327–1360 (2014); the standard treatment of the Agincourt campaign is Anne Curry’s Agincourt: A New History (2005) and her The Battle of Agincourt: An Anatomy (2020). The two standard French treatments are Christophe Gilliot’s edition of the Vie du Prince Noir and Contamine’s Azincourt (1964).

The mud

The most immediate tactical factor was the ground. The fields of Picardy had been ploughed by the autumn rains, and the field of Agincourt was a churned morass of clay, two feet deep in places. The French men-at-arms, in plate armour of 60 to 80 pounds, who expected to close with the English line, sank to their knees at every step. The longbowmen, lightly armoured, were able to move freely. The mud turned what would have been a heavy infantry action into a slaughter.

The losses

Modern estimates of the English losses cluster around 400 to 600 killed. The French losses, of all ranks, are conventionally estimated at between 1,500 and 4,000 — the chroniclers’ figures of 10,000 or 16,000 are demonstrably rhetorical — but the political effect of the loss was greater than the absolute numbers would suggest. The three peers killed — the duke of Alençon, the duke of Brabant, and the count of Nevers — were the cream of the French aristocracy. The constable d’Albret was killed, and the dukes of Orléans and Bourbon were captured. The French second estate had been decapitated in a single morning.

The political consequences

Agincourt did not end the war. It did, however, change the political arithmetic. The English conquest of Normandy (1417–1419) followed from a French nobility too depleted to mount a serious defence. The Treaty of Troyes of 21 May 1420, by which Charles VI recognised Henry V as regent and heir of France, was the political settlement that Agincourt had made possible. The disasters of 1415–1420 were, in effect, the disasters of Agincourt multiplied across five years of war and diplomacy.