The Outnumbered English Army That Defeated a Substantially Larger French Force at Agincourt on Saint Crispin's Day in 1415 With the Help of the Longbow and Heavy Mud

Henry V had become king of England on 21 March 1413. The political objective of his reign was the recovery of the French territories that the Angevin kings had lost across the 13th and 14th centuries. The Hundred Years’ War (1337-1453) was technically ongoing but had been dormant since the truce of 1389. Henry restarted it in 1415.

His invasion force of approximately 12,000 men landed at the mouth of the Seine in August 1415 and besieged Harfleur. The siege took five weeks. Dysentery during the siege killed or invalided approximately 2,000 of his troops. By the time Harfleur fell on 22 September 1415, Henry’s effective field force was reduced to about 8,000 men.

He decided to march overland to the English-held port of Calais — a distance of about 100 miles — rather than re-embark from Harfleur. The march took 16 days through wet autumn weather across northern France. The French army, mobilising slowly, intercepted him at the village of Agincourt on 24 October 1415.

The field

The chosen battlefield was a narrow stretch of recently ploughed field between the woods of Agincourt and Tramecourt — approximately 750 metres across at the widest point. Heavy autumn rains had turned the ploughed ground into a deep mud. The French army of approximately 25,000 (modern estimates range from 12,000 to 36,000; Anne Curry’s 2005 reconstruction settles on roughly 25,000) was three times larger than Henry’s force.

The French command was divided. The senior French commander Charles d’Albret, the Constable of France, was nominally in charge, but the army included approximately twenty senior French nobles each commanding their own retinues with their own ideas about tactics. Charles VI himself was not present — he was suffering one of his recurrent episodes of mental illness — and his son the Dauphin was under royal orders not to risk himself.

The battle, 25 October 1415

Henry deployed his army in the standard English defensive formation: heavy infantry in the centre, longbowmen on both flanks. The longbowmen drove wooden stakes into the ground at angles to obstruct cavalry charges. Henry’s archers numbered approximately 6,000 — about three-quarters of his army.

The English advanced about 200 metres at dawn into longbow range of the French lines and stopped. Henry was effectively daring the French to attack across the deep mud. After approximately three hours of waiting, the French moved.

The French heavy-cavalry charge on the English flanks was destroyed by the longbow stakes and the volume of arrow fire. The retreating French cavalry collided with the advancing French infantry. The French infantry, in plate armour, slogged across the mud toward the English position at a reduced pace. They arrived exhausted.

The hand-to-hand fighting that followed produced French casualties at higher rates than English ones for several reasons. The French were exhausted from the mud crossing; their heavy plate armour was both protective and immobilising once they had been knocked down; the longbowmen, now without arrows, joined the melee with mallets, daggers, and short swords; and the press of French troops behind the front rank meant that fallen French knights were trampled rather than rescued.

The prisoners

Approximately 1,500 French prisoners were taken to the English rear during the morning. Around midday a small French rearguard force attacked the English baggage train, and a rumoured second French main force was reported to be regrouping for an attack.

Henry, with prisoners behind him and the possibility of a renewed French attack in front, ordered the prisoners killed. The order was specifically that the senior nobles should be spared (for ransom) but the lower-ranking prisoners should be killed immediately. The killings were carried out by Henry’s archers, who used daggers because the prisoners were already disarmed. Approximately 1,500 were killed in less than an hour.

The order was theologically and legally controversial at the time — the killing of unarmed prisoners violated contemporary military convention — but Henry’s defence was that the operational situation required it. The renewed French attack did not actually materialise; the rumour had been false.

What followed

The conventional casualty figures are approximately 6,000-10,000 French dead and fewer than 500 English. The high estimate of French casualties may be partly inflated by contemporary English chroniclers but is supported by archaeological work at the field and by the documented number of French noble families that lost their heads of household. The senior French casualties were catastrophic — three dukes, eight counts, ninety barons, and approximately 1,500 knights.

Henry reached Calais on 29 October 1415 and returned to England in November. He was received in London as a military hero. The 1420 Treaty of Troyes that followed his subsequent campaigns recognised him as regent of France and heir to the French throne. He died of dysentery at the Bois de Vincennes on 31 August 1422, aged 35 — two months before the death of the French king Charles VI whom he had been designated to succeed.

The infant Henry VI inherited the dual claim. His weak reign and the English-French defeat that followed under Joan of Arc’s campaigns from 1429 (see Joan of Arc’s trial) reversed the Agincourt-era English position. The Hundred Years’ War ended in 1453 with the English expelled from all French territories except Calais.

Shakespeare’s Henry V, written approximately 184 years after the battle, codified the canonical English-language memory of Agincourt as a heroic triumph against overwhelming odds. The play’s St Crispin’s Day speech — “We few, we happy few, we band of brothers” — is the most-quoted English-language military oration. The play omits the killing of the prisoners.