Practices case study — warfare in the Spanish conquest

In 1519 a Spanish adventurer named Hernán Cortés landed on the coast of Mexico with about 500 men. Within two years he had helped bring down the Aztec Empire, a state of several million people. How did such a small force achieve so much?

Part of the answer is simple: the two sides fought with completely different tools of war. This micro looks closely at the practices of that fighting — the weapons, the diseases and the alliances — as a case study you can use to argue what really decided the outcome.

The big idea: The Spanish conquest of the Aztec and Inca empires (1519–1533) is a textbook case for essays on how technology, disease and alliances — not just numbers — can determine the outcome of a war.

Steel versus obsidian

Aztec and Inca warriors were skilled and brave, but their weapons came from the Stone Age toolkit. Their main close-combat weapon was the macuahuitl, a wooden club lined with razor-sharp obsidian blades.

Obsidian could slice flesh terrifyingly well, but it was brittle — it shattered on impact with metal. Spanish soldiers, by contrast, carried steel swords and wore steel armour and helmets.

Steel held its edge through blow after blow and did not snap the way obsidian did. Spanish armour also stopped many blows that would have wounded an unarmoured man, so individual Spanish soldiers could often survive fights that would have killed an Aztec warrior.

The horse: a weapon nobody in the Americas had seen

Perhaps the single greatest shock was the horse. There were no horses anywhere in the Americas before the Spanish arrived, so Aztec and Inca warriors had never faced a mounted charge.

Terror on the battlefield: Spanish accounts describe Aztec warriors initially believing horse and rider were one terrifying creature. A charge of even a dozen mounted lancers could break a much larger formation of infantry who had no experience of fighting cavalry and no weapon designed to stop one.

Horses gave the Spanish speed, height and shock power all at once — a lancer on horseback could strike down at foot soldiers before they could land a blow in return, then wheel away out of reach.

Gunpowder and steel armour add to the gap

The Spanish also carried gunpowder weapons: arquebuses (an early type of gun) and small cannon. These were slow to reload and not very accurate, but the noise, smoke and flash caused real panic among warriors who had never heard gunfire.

Not a numbers game: Cortés had only a few hundred Spanish soldiers against an Aztec Empire of millions, and Pizarro had under 200 men when he captured the Inca emperor Atahualpa in 1532. The huge imbalance in numbers makes the technology gap even harder to ignore as an explanation for the outcome.

Weapons alone cannot explain how a few hundred Spaniards helped topple an empire of several million people. The single biggest factor was one nobody could see coming: disease.

The big idea: The Americas had been isolated from Europe, Asia and Africa for thousands of years, so indigenous peoples had no immunity to Old World diseases like smallpox. When Europeans brought these diseases, the results were catastrophic.

Smallpox reached Mexico in 1520, carried by a Spanish soldier who had come with a relief expedition. It swept through the Aztec population, who had never encountered the virus and had built up no resistance to it over generations.

The death of an emperor: The Aztec ruler Cuitláhuac took the throne in 1520 after Moctezuma II's death, but he himself died of smallpox within about 80 days. Losing two rulers in quick succession threw the empire's leadership into chaos at the exact moment it needed to organise resistance.

The pattern repeated in South America. Smallpox likely spread ahead of the Spanish themselves, reaching the Inca Empire by the mid-1520s and killing the emperor Huayna Capac around 1527.

Disease triggers civil war in the Inca Empire: Huayna Capac's death without a clear heir sparked a civil war between his sons Atahualpa and Huáscar. This war had already devastated and divided the empire before Pizarro's small force even arrived in 1532 — Pizarro was lucky enough to exploit an empire already at war with itself.

A powerful essay point: Disease is one of the strongest pieces of evidence that factors beyond leadership or tactics decided this war. An emperor dying of smallpox, or an empire already fighting a civil war caused by an epidemic, happened before a single major battle — a strong basis for arguing disease was the single most decisive practice/factor.

Technology and disease explain a great deal, but the Spanish also won because they were never really fighting alone. Both Cortés and Pizarro built alliances with local peoples who had their own reasons to fight alongside them.

The Tlaxcalans: the alliance that made the conquest possible

The Tlaxcalans were a powerful people who had long resisted Aztec domination and paid no tribute to Tenochtitlan. When Cortés marched inland in 1519, the Tlaxcalans fought him fiercely at first — but after heavy losses, their leaders chose to ally with the Spanish against their old enemy, the Aztecs.

Why the Tlaxcalans mattered so much: Tens of thousands of Tlaxcalan warriors joined Cortés's campaign. Without this alliance, historians agree the tiny Spanish force could never have besieged and taken Tenochtitlan, a city of perhaps 200,000 people built on a lake.

Not a Spanish war alone: It is more accurate to describe the fall of Tenochtitlan in 1521 as a war fought mainly by indigenous warriors, led and reinforced by a small core of Spanish soldiers with superior technology — not simply 500 Spaniards conquering an empire single-handedly.

Leadership: Cortés and Pizarro

Personal leadership also mattered. Cortés was ruthless and adaptable: he burned his ships in 1519 so his men could not retreat, and he used Malinche — an enslaved woman fluent in Nahuatl and Maya — as an interpreter and adviser who helped him negotiate alliances like the one with Tlaxcala.

In Peru, Francisco Pizarro used deception rather than pitched battle. In 1532 he invited the Inca emperor Atahualpa to a meeting at Cajamarca, then ambushed his lightly-armed escort, killed thousands of Inca soldiers and courtiers, and captured Atahualpa himself.

Capturing the ruler as a war-winning tactic: Both leaders understood that in a highly centralised empire, seizing or killing the ruler could paralyse the whole state. Atahualpa's capture, followed by his execution in 1533, left the Inca Empire without clear central command exactly when it needed to organise resistance.

Don't oversimplify to 'one cause': It is tempting to say technology alone won these wars, but disease weakened both empires before major fighting even began, and indigenous allies supplied the bulk of the manpower against the Aztecs. A strong essay always weighs several practices together.