King Henry V. (Credit: The Print Collector/Print Collector/Getty Images)

1. Henry V pawned some of the crown jewels to fund his invasion of France.

In August 1415, King Henry V led an 11,000-strong army from Southampton to Normandy with the goal of regaining lost territory and asserting a longstanding English claim to the French throne. The invasion required huge numbers of men and arms and involved an armada of hundreds of ships—none of which came cheaply. To finance his quest, Henry persuaded Parliament to levy new taxes and also borrowed large sums from wealthy English citizens and cities. London alone loaned him the modern equivalent of around $5 million. As a guarantee of repayment, Henry gave his backers various pieces of royal treasure including jewels, a gold collar called the “Pusan d’Or” and even a ruby and diamond-encrusted crown that had once belonged to King Richard II.

2. The English lost a third of their troops to disease before the battle even took place.

Upon landing in northern France, Henry marched his army to the mouth of the Seine and besieged the strategically important city of Harfleur. The 28-year-old expected the town to fall in a few days, but the siege dragged on for five grueling weeks, during which at least a third of his army was killed or incapacitated by dysentery. The king pressed on toward Calais, however, eventually covering some 200 miles in 16 days before being blocked by a French army near the modern day village of Azincourt. When the battle finally began on October 25, the English were exhausted, filthy and nearly starving. Many were also reeling from the stomach-turning effects of dysentery. According to historian Juliet Barker, some of Henry’s archers “were reduced to cutting off their soiled breeches and undergarments in an attempt to allow nature to take its course more easily.”

Henry V praying before the Battle of Agincourt. (Credit: The Print Collector/Print Collector/Getty Images)

3. Henry V ordered his men to spend the night before Agincourt in silence.

Most scholars believe the Battle of Agincourt pitted a scant 6,000 to 9,000 Englishmen against a French force totaling anywhere from 12,000 to 36,000. Fearing an ambush by his much larger enemy, Henry V kept discipline in his ranks by demanding that his troops pass the night of October 24 in absolute silence. Men-at-arms and knights were warned that disobeying the order would cost them their horse and harness. The lower ranks, meanwhile, were threatened with the loss of their right ear.

4. The English force was mostly made up of archers—and they may have won them the battle.

Of the roughly 8,000 troops Henry had at Agincourt, only around 1,000 to 2,000 were men-at-arms and knights with heavy plate armor. The rest were English and Welsh archers equipped with the English longbow, a weapon known for its deadly range of fire. Henry deployed his archers on the flanks of his line behind a protective palisade wall of sharpened wooden stakes. When French cavalry and men-at-arms charged the English position, the bowmen let loose with a flurry of arrows so thick that it supposedly darkened the sun. French nobles and knights went down in droves, many of them hit by multiple arrows fired with enough force to penetrate armor. Others were trampled by horses that had been spooked by the storm of projectiles. Once the French force panicked and became bunched together, the English archers traded their bows for poleaxes and lead mallets and joined their knights in a counterattack. The resulting massacre left between 6,000 and 10,000 French troops dead. The English only lost a few hundred men.

Drawing of an English bowman. (Credit: MPI/Getty Images)

5. A muddy battlefield and heavy armor played a major part in the French defeat.

Along with the hail of arrows from English archers, the French advance was also hampered by the deplorable condition of the battlefield. Several days of torrential rains had turned the recently tilled ground at Agincourt into a soggy morass. Already weighed down by their heavy metal armor, the French knights were forced to slip and slide their way toward the English line, often sinking down to their knees in mud. Those lucky enough to survive the slog arrived at the enemy position exhausted and disorganized, while many others were caught in a human crush and either trampled or suffocated to death after they fell into the mire. Since most of the English weren’t wearing armor, they were able to pounce on the weary Frenchmen and inflict devastating casualties.

6. A group of French knights made a pact to kill Henry V at Agincourt.

According to the Burgundian chroniclers Jean Waurin and Jean le Fevre, a band of 18 knights under the banner of the lord of Croy met before the battle and vowed to kill Henry V and knock his crown from his head. The entire group supposedly died in the effort, but one member did manage to strike Henry’s helmeted head with an axe and chip off a piece of his crown. The blow wasn’t the only brush with death the king had while fighting on the front lines. When his younger brother Humphrey was wounded in the groin, Henry is said to have kept a group of French attackers at bay until he could be carried to safety.

(Credit: Fine Art Images/Heritage Images/Getty Images)

7. The English massacred many of their French prisoners.

Shortly after the defeat of the main French force, a rumor spread through the English ranks that the French were gearing up for a second assault. The attack never materialized, but Henry V grew worried that the many French prisoners his men had taken might rise up against them if the battle were renewed. Ignoring the rules of war, the king commanded his army to execute all the enemy troops in their custody, save for a few dukes and other illustrious men. Just how many Frenchmen were murdered is uncertain, but the number may have been as high as 2,200. According to an account by a French knight, one group of around a dozen prisoners was locked inside a house that was then set ablaze. Though not particularly controversial at the time—even the French chroniclers didn’t fault Henry for his actions—many have since labeled the killings an early example of a war crime.

8. The English won the battle, but lost the war.

While Agincourt ranks as one of the most one-sided victories in medieval history, it didn’t have any major implications for the outcome of the Hundred Years’ War. The English sailed home after the battle and didn’t return to France until 1417, when Henry V launched a successful campaign that ended with a treaty establishing him as the successor to the French King Charles VI. Henry died before he could claim the throne, however, and the French later rallied behind the likes of King Charles VII and the teenaged military leader Joan of Arc. Over the next several decades, a resilient France retook Paris, Normandy and several other key regions. By the time they were defeated at the Battle of Castillon in 1453—the traditional end date for the Hundred Years’ War—the English had lost nearly all of their French territories.

Objects from the Battle of Agincourt on display at the Tower of London on October 22, 2015, to commemorate the battle’s 600th anniversary. (Credit: Dan Kitwood/Getty Images)

9. Shakespeare helped make Agincourt famous.

Even though it didn’t win them the Hundred Years’ War, the triumph at Agincourt became an enduring part of English national myth. The battle was celebrated in patriotic poems and hymns, and was later immortalized by William Shakespeare in his play “Henry V,” which includes the famous St. Crispin’s Day speech in which Henry calls his army “we happy few, we band of brothers.” The Bard’s stirring dialogue helped make “Henry V” and the upset at Agincourt into a recurring wartime rallying cry for the British. The play was used to keep the public’s spirits up during the dark days of World War I, and Winston Churchill later encouraged Laurence Olivier to make a film version during World War II.