The Amazing True Story of The Battle of Agincourt
You might have seen Henry V, the 1989 movie with Kenneth Branagh set at the famous battle of Agincourt. Were we to believe Will Shakespeare, King Henry and his squires won the battle from pure gusto. The reality, however, was far more interesting and replete with lessons still applicable today.
First, you have to understand the context. King Henry thought France had confiscated lands in Normandy that England rightfully owned, and so he landed in northern France to reclaim them. After storming Harfleur, his army of 12,000 had dwindled down to less than 7,000, so Henry chose to retreat north to the British stronghold of Calais to re-equip. However, the French had been trailing Henry and forced all his troops into a narrow field bracketed by two woods, Agincourt and Tramecourt. It's hard to tell how many French forces stood before Henry, but we do know the French easily outnumbered the Brits by 3 to 1, and maybe as much as 4 to 1 or 5 to 1. As if that weren't bad enough, the Brits had been marching 260 miles for two and a half weeks and were still suffering from a bout of dysentery. 
The British had a few technological advacements on their side. One was the longbow used by the Welsh archers. The longbow was taller than any other bow, and thus had greater power and range, all adding up to one deadly advantage: from a distance, the British could safely hurl lethal arrows at the gathering French forces.
The other technological advancement was the archers' "palings", pointed wooden stakes buried into the ground at a sharp angle to deter an equestrian attack. (Fun fact: palings are the origin of the phrase, "beyond the pale", meaning something placed outside the protected area).
Those two modern weaponry advancements were pivotal in the battle of Agincourt, but the longbow was especially crucial for one unique reason: the French considered the longbow unchivalrous.
Frequently unmentioned in the history books is the importance chivalry played at Agincourt. The French believed strongly in chivalry, a code of honor, about what was fair and morally right on a field of battle. The longbows, and the commoner longbowmen wielding them, were viewed as beneath the French. The French likely felt they had the superior moral ground and would show the British commoners how they could still win without using a disgraceful longbow.
To counteract the longbow, the French used thicker armor, but thicker also meant heavier—armor could have weighed as much as 40 to 60 pounds—and that meant less agility: French knights would have had to mount their horses with the help of many more squires, and probably a set of pulleys, too. An unmounted knight during battle, weighed down with heavy and inflexible armor was little more than a beetle squirming on its back, and had little hope of even getting up, much less re-mounting his horse.
The French knights were undeterred. They would attack by horse and during the attack, the "disreputable" Welsh archers would rain down devastating longbow arrows that pierced the approaching steed's unprotected backside... and off the knights would be thrown. Any knight miraculously still seated on his horse who reached the archers would suddenly see the archers retreat safely behind their large wooden palings... and the knights would either dismount and stumble through the palings or be forced to retreat. In both cases, that would mean still more arrows from the archers.
Steeped in courtly etiquette and a strong moral code of conduct, the French elected not to use the longbow because they thought its use was unfair and a dishonorable way to conduct warfare...
...and they lost.
The French failed to win a battle they dominated in manpower. Why? Because they were too caught up with what they thought was "right", when they should have been looking at what was working. Right or wrong, longbows worked. Had the French swallowed their pride and returned their own longbow volley, they would have obliterated the Brits. But their delusion of moral superiority lost them the battle of Agincourt, and handed an unequivical victory to their foes which rings throughout history to this day.
The larger lessons of Agincourt are how a marginalized group can turn the tables against a vastly larger foe, and how a superior force should never become so enamored with its "moral superiority" that it won't review and/or adopt new strategies with a mind unfettered by ideological prejudice. (I put "moral superiority" in quotes because what we consider "morally superior" today is radically different than what previous generations have defined it, as no doubt future generations will look at our own "moral superiority" and scratch their heads in confusion.)
History offers countless examples of how small groups of people chose a time and place of battle best suitable to them to win a war against an impossible opponent: American revolutionaries used "dishonorable" geurilla tactics against the British, Afgan mujahadin whittled down their Russian occupiers, the Vietcong picked off Americans troops, the Algerians subverted the French... in each case, the larger force should have easily won the war or battle, but they didn't. Sure, we can point to any number of other factors as to why each case is unlike the other, but these examples all illustrate the very same lesson from Agincourt: to effectively fight and beat a smaller opponent, the larger opponent must be willing to adopt the same tactics employed by their smaller opponent no matter how dishonorable or morally questionable those tactics may seem at the time. History shows us now that the longbow wasn't dishonorable at all. Quite remarkably, the morally questionable part of this scenario was the stupid chivalrous attitude preventing the French from using the longbow.
The French didn't lose at Agincourt due to a lack of resources, but from a moral "blindness", an willingness to see things as they really were and adapt to the situation before it was too late.
