A narrow gap means only a limited number of men can pass simultaneously.
Terrain converts geometry into combat power.
Edward did not need the hedges to stop the French completely.
He needed them to slow and channel.
Once the French entered the channels, arrows and men-at-arms did the rest.
The landscape therefore functioned like an invisible ally.
A Larger Army Needs Space
This is one of Poitiers' simplest lessons.
More men require more room.
If the battlefield denies that room, numbers can become congestion.
A smaller army may then achieve local equality.
Edward understood this.
John never found a way to overcome it before cohesion deteriorated.
The French king had more power in total.
Edward had enough power at the points where men could actually fight.
That difference explains the battle better than heroic mythology.
Fatigue Accumulated Unequally
The defenders were tired.
So were the attackers.
Yet attacking across difficult ground imposes a different cost.
French men had to move through arrow fire before reaching close combat.
If they withdrew, they crossed ground again.
Replacement divisions then repeated the process.
Edward's men also fought hard, but many began from stationary positions.
They could preserve energy until contact.
Over several hours, the asymmetry mattered.
A French soldier arriving at the English line might already have spent significant effort.
An English man-at-arms meeting him had spent less moving and more waiting.
Small physiological differences become tactical differences when repeated across thousands of men.
Armor Was Not Impossibly Heavy, but It Was Not Weightless
Modern experiments have shown that well-made medieval armor allowed substantial mobility.
Knights were not clumsy metal statues.
They could run.
Mount horses.
Climb.
Fight.
That does not mean marching and fighting in armor required no energy.
Heat, stress, uneven ground, restricted breathing through helmets, and repeated exertion all accumulated.
Poitiers punished endurance.
The French choice to dismount protected them from one danger while increasing another.
Again, tradeoffs.
The Archers Were Not Invulnerable Either
Had French cavalry broken through successfully, exposed archers could have been destroyed quickly.
That is why the initial mounted assault mattered.
Edward's defensive system depended on preventing the French from disrupting the missile troops before the larger infantry attack arrived.
The early English success therefore had disproportionate importance.
Archers remained active.
The later divisions inherited the problem.
Small tactical failures create larger operational consequences.
The Battle Was Won Through Accumulation
One horse falls.
One marshal dies.
Another commander is captured.
One division slows.
Another becomes tired.
A withdrawal begins.
A supporting formation interprets it badly.
The king advances.
A reserve remains unused on the English side.
A mounted group circles.
The front moves forward.
The rear feels threatened.
One group runs.
Another follows.
The king becomes isolated.
No single moment contains the whole victory.
The famous counterattack works because all the earlier moments have already changed the battlefield.
This is how complex systems collapse.
Gradually.
Then suddenly.
The Counterattack Was the Release of Stored Advantage
Edward's restraint before it mattered.
Every soldier not committed earlier became potential energy.
Every surviving archer mattered.
Every commander still communicating mattered.
The prince's reserve was not simply spare manpower.
It represented future choice.
Once Edward recognized French disorder, he spent that choice.
The investment paid.
This is why reserves matter in battle.
A commander without one can only endure whatever is happening.
A commander with one can change what happens next.
The Captal de Buch Converted Mobility Into Fear
His mounted troops did not have to defeat the entire French army physically.
Their appearance behind or beside the French altered information.
Information drives morale.
Men who believe escape is closing become more likely to flee early.
Men who see others flee become more likely to believe encirclement is real.
The psychological effect can grow faster than the actual cavalry force.
Position multiplies power.
This principle appears repeatedly across military history.
Poitiers offers a classic example.