October 25, 1415 was an amazing day for the English. The English longbow had long proved during the Hundred Years War to be a devastating weapon in the hands of skilled archers, but rarely had the English faced such long odds as they did at Agincourt. Approximately 6,000 English, exhausted and worn from their march, faced approximately 30,000 French. About five out of six of the English were archers with the remainder men-at-arms, knights and nobility. The French had about 10,000 men-at-arms, knights and nobility, and 20,000 archers, crossbowmen and miscellaneous infantry.
The English established their battle line between the woods of Agincourt and Tramecourt, which offered excellent protection to both of their flanks. The English archers made up the front line with stakes set in the ground before them to impale charging horses. Archers were also placed in the woods to provide flanking fire against advancing French. The men at arms and knights and nobility, were divided into three forces behind the archers. They fought on foot.
The terrain between the woods that the French would have to cross in their attack of the English consisted of newly ploughed, and very muddy, fields. Having walked through muddy fields on several occasions in rural Illinois, I can attest that simply getting from point A to point B in such terrain can be exhausting, let alone fighting at the end of the tramp through the morass.
For three hours there was no fighting, the French waiting for reinforcements. King Henry tiring of this had his army advance to put pressure on the French to attack. Alarmed by this offensive movement by the English, the French finally attacked.
The French advanced in three battles, or lines, one behind the other. The mounted French, only about 1200 men, were in the first line. All the other French fought afoot.
The charge of the mounted French was a complete disaster and set the tone for the entire battle. Due to the woods, the English archers could not be outflanked, and their blizzard of arrows wreaked havoc with the horses of the French as they made their frontal charge. The French cavalry fell back on the advancing dismounted French men-at-arms. These advanced against heavy fire from the longbowmen, who fired into the French men-at-arms until they ran out of arrows, and then joined in the melee with the English men-at-arms. The French initially succeeded in forcing back the English line. However, their success was short-lived. Exhaustion set in among the French after their trek through the muddy fields, and the English longbowmen, wearing no armor and therefore much more agile than their adversaries in the mud, attacked with surprising success, aiming their blows at unarmored portions of the bodies of the French men-at-arms. The fighting lasted about three hours before the French withdrew in defeat. The stunned English slowly realized that they had won one of the most incredible against the odds victory in military history.