For most of the Middle Ages, the deadliest thing on a battlefield was a wall of armoured men on horseback.
These were the knights, and they were the elite fighting force that shaped how wars were fought.
A knight rode a heavy warhorse and wore chainmail or, later, plate armour.
His great weapon was the mounted charge, where a tight line of horsemen crashed into the enemy at speed.
Why cavalry dominated: A charge of heavy cavalry could shatter foot soldiers in seconds through sheer weight and terror. Because only wealthy nobles could afford a horse, armour and years of training, knights were both a military elite and a social elite — war and status were tied together.
But knights could not fight alone. Kings needed numbers, so they raised the rest of the army through the feudal levy.
- Feudal levy — lords owed the king a set number of days of service each year in return for their land, and brought their own men.
- The problem — service was usually limited to about 40 days, so armies melted away just when a long campaign or siege needed them most.
- Untrained and unwilling — levies were often farmers pulled from their fields, not professional fighters, and their quality varied wildly.
Because levies were so unreliable, rulers slowly turned to soldiers they could simply hire and keep.
This was the shift towards mercenaries and standing paid forces.
Feudal levy
- Served out of feudal duty, unpaid
- Only obliged for a short term (~40 days)
- Often untrained farmers of mixed quality
- Went home at harvest — army shrank fast
- Cheap for the king but unreliable
Paid mercenaries / professionals
- Fought for money and stayed as long as paid
- Available all year, including long sieges
- Skilled specialists (crossbowmen, pikemen)
- Loyal while wages arrived — dangerous if not
- Expensive, so needed strong royal finances
The money link: The move to paid armies made war depend on cash. A king who could tax and borrow could keep an army in the field for months; a king who ran out of money saw his mercenaries desert or mutiny. War-making and royal finance became inseparable.
Mobilization of human and economic resources
Everything above — knights, levies, mercenaries, taxes — is really one syllabus concept in disguise: mobilization of human and economic resources.
Examiners use this exact phrase, so it is worth learning it by name. It asks a single question: where did a medieval ruler get the men to fight, and the money to pay them?
- Feudal levy — unpaid service owed by nobles in return for land; cheap but capped at ~40 days.
- Pay — hiring mercenaries or a paid retinue; kept an army in the field indefinitely, but only as long as wages arrived.
- Taxation — direct levies on land, income or trade, raised by a king to fund pay, supplies and castle-building.
- Tribute — payments extracted from a defeated or threatened enemy, used to fund further campaigns without taxing your own subjects.
- Allies — troops and money supplied by another ruler or power bound by treaty or marriage, mobilizing resources you did not have to raise yourself.
How to use this in an essay: A strong answer on 'mobilization of resources' does not just describe armies — it explains the method of raising them (levy, pay, tribute or alliance) and the method of funding them (taxation or loans from bankers and merchants), then judges which combination let a ruler sustain a war and which left them unable to continue.
Taxation alone rarely covered a long war. Rulers also turned to loans — borrowing from Italian banking houses or wealthy merchants against future tax income — to bridge the gap between when soldiers needed paying and when tax revenue actually arrived.
A ruler who could combine taxation, loans and tribute could field a paid, professional army for years; one who relied on the feudal levy alone could rarely campaign for more than a season.
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Pitched battles between two armies were actually rare in the Middle Ages.
Far more common was the siege — the slow, grinding attack on a castle or walled town.
Why castles mattered: A castle let a small garrison control a large region. Attackers could not safely leave an enemy stronghold behind them, so taking castles — not winning open battles — was often the real key to conquering territory.
Castle design was a science of survival. Builders added thick walls, towers and clever features to make attack as costly as possible.
- Thick stone walls — replaced early timber to resist fire and battering.
- Round towers — curved walls deflected missiles and had no weak corners to undermine.
- The moat — a water-filled ditch that stopped attackers reaching the base of the wall or digging beneath it.
- Murder holes and arrow slits — let defenders strike attackers while staying protected.
- Concentric design — rings of walls, one inside the next, so breaking through one still left another.
To take a castle, an attacker had two broad choices: starve it out or break in.
The patient method was the blockade.
Blockade and starve
Surround the castle so no food, water or reinforcements get in. Cheap in lives but slow — a well-stocked castle could hold out for months.
Batter the walls
A battering ram — a heavy beam swung against the gate or wall — smashed at the weakest points to force an opening.
Bombard from range
The trebuchet, a giant counterweight sling, hurled heavy stones over or into the walls to crack them and crush defenders.
Mine underneath
Dig a tunnel under a tower, prop it with timber, then burn the props so the ground and wall above collapsed.
Starve, batter, bombard, or mine — four ways past a wall.
The trebuchet was the artillery of its age.
It could throw rocks weighing over 100 kg, and besiegers sometimes even flung dead animals over walls to spread disease.
Mining in action: At the siege of Rochester Castle in 1215, King John's men dug beneath a corner tower and used the fat of forty pigs to burn the wooden props. The tower crashed down, and the castle fell — a vivid example of how siege engineering, not open battle, decided campaigns.
Women and war: rulers, defenders and providers
The IB syllabus specifically asks you to study the role and significance of women in medieval warfare — not just as bystanders but as active participants in four distinct ways.
Women's involvement was shaped by the same castle-and-siege world you have just studied: when a lord went to war, someone had to hold the keep behind him.
- Rulers and regents directing war — Noble and royal women governed kingdoms and ordered campaigns while their husbands or sons were on crusade or in captivity. They raised taxes, negotiated truces, and organised military recruitment.
- Defenders of towns and castles under siege — When a garrison was depleted or its lord absent, noblewomen took formal command of the defence. They directed archers and engineers, managed food supplies, and conducted negotiations with besieging forces.
- Camp followers and material providers — Armies could not move without the large numbers of women who cooked, carried supplies, nursed the wounded, laundered equipment, and traded goods. Their labour was part of the logistics of every major campaign.
- Symbolic and inspirational figures — Women were also deployed as symbols of cause and legitimacy. The most famous example, Joan of Arc, showed that a woman's symbolic power could be militarily decisive.
Eleanor of Aquitaine — regent and war-director (12th century)
Queen of France then England, Eleanor governed England as regent while Richard I was on crusade and in captivity (1190–1194). She raised the enormous ransom of 150,000 marks to free him — a feat requiring the full mobilisation of royal finances and administration. She had earlier participated in the Second Crusade (1147–1149). Eleanor shows how a woman at the top of feudal hierarchy could shape military outcomes without a battlefield.
Nicola de la Haie — defender of Lincoln Castle (1191, 1216–1217)
Nicola inherited the constableship of Lincoln Castle and personally commanded its defence twice. In 1216–1217, during the First Barons' War, she held Lincoln against rebel barons and French forces for months while England's new king Henry III was a child. Her defence of the castle was a direct military contribution that helped stabilise the Plantagenet kingdom.
Joan of Arc — the symbolic turning point (1429–1431)
By 1429, England controlled northern France and the city of Orléans was under siege. A teenage peasant girl named Joan convinced the French Dauphin (future Charles VII) that she had divine instructions to lead his army. She rode with the troops, carried the royal standard, and lifted the Siege of Orléans in just nine days. French forces then won a series of victories and Charles was crowned king. Joan was captured, tried by a pro-English Church court, and burned at the stake in 1431 aged about 19. Her significance is both military (she reversed the momentum of the war) and symbolic (she embodied French national cause and Catholic legitimacy).
Camp followers — the invisible army
Every medieval army trailed a large body of non-combatants, the majority of them women. They supplied cooked food, repaired clothing, cared for the sick and wounded, carried water, and sold goods from market towns. Without them, armies could not sustain themselves in the field. Chroniclers often ignored camp followers, but commanders and logisticians knew they were indispensable — their absence could end a campaign faster than any enemy.
How the examiner tests this: A Paper 2 question on Topic 2 might ask you to discuss 'the role of women in medieval warfare' or to evaluate how far war was an exclusively male activity.
Hit all four categories — ruler/regent, castle defender, camp follower, symbolic figure — and name at least two specific individuals (e.g. Eleanor of Aquitaine directing the ransom effort; Joan of Arc lifting the Siege of Orléans 1429). Avoid vague claims: say what the woman actually did and what military effect it had.
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For centuries the knight ruled the battlefield — but new weapons slowly chipped away at that power.
The first great challenger was the longbow.
The longbow's power: A trained English longbowman could loose ten or more arrows a minute and punch through armour at range. Massed volleys could break a cavalry charge before it landed, meaning cheap common archers could now defeat expensive noble knights.
The longbow proved itself in the Hundred Years' War.
At Crécy in 1346 and Agincourt in 1415, French knights charged into storms of arrows and were slaughtered.
Then came a weapon that would change war forever: gunpowder.
It arrived in Europe in the 1300s and grew steadily more important through the 1400s.
Early cannon
The first cannon were clumsy, slow to load and prone to bursting. But by the mid-1400s, big siege guns could smash castle walls that had resisted attack for centuries — making the old stone castle suddenly vulnerable.
Early firearms
Handheld guns were inaccurate and fired only once before a long reload. Yet a gun needed little training, so a poor man with a firearm could kill a knight who had trained since childhood.
The end of the knight
Together, longbow and gunpowder began the slow end of the armoured knight's dominance. Skill and noble birth mattered less; numbers, drill and firepower mattered more.
The fall of Constantinople, 1453: The Ottomans battered the mighty walls of Constantinople with enormous cannon, some so large they took hours to reload. When the walls finally broke, the thousand-year-old city fell — the clearest sign that gunpowder had ended the age of the invincible fortress.
War at sea
Medieval navies rarely fought grand sea battles.
Their main job was to move armies, guard supply lines and raid enemy coasts.
- Transport of armies — ships carried troops, horses and supplies to where they were needed, as with the Norman crossing to England in 1066.
- Control of the sea — dominating the sea kept your supply routes open and cut off the enemy's, deciding whether a campaign could be fed.
- Coastal raiding — fast raids on enemy shores burned towns, seized loot and spread fear far from the main front.
Sea power was support power: In this era the sea usually shaped war indirectly — by carrying and supplying armies — rather than through decisive fleet battles. Whoever controlled the crossing often controlled the campaign.