Aztecs and the Spanish conquest, 1519-1535 Revision Notes
Subject: History | Level: GCSE | Exam Board: OCR
The collision between the Aztec Empire and Hernán Cortés's Spanish expedition between 1519 and 1535 represents one of history's most consequential encounters: a sophisticated Mesoamerican civilisation of millions was brought to its knees within two years, reshaping the Americas forever. For OCR GCSE candidates, this World Depth Study demands precise causal analysis — explaining not just what happened, but why a handful of Spanish soldiers, allied with tens of thousands of indigenous warriors and aided by catastrophic disease, could topple an empire that dominated central Mexico. Mastering this topic means understanding the interplay of military technology, biological catastrophe, indigenous alliances, and Aztec internal divisions — and being able to deploy that understanding fluently under exam conditions.
Revision Notes & Key Concepts
Revision Podcast Transcript
OCR GCSE HISTORY PODCAST — THE AZTECS AND THE SPANISH CONQUEST, 1519 TO 1535 A 10-Minute Revision Episode for OCR B (SHP) World Depth Study INTRO (approx. 1 min) Welcome back to your GCSE History revision podcast. I'm so glad you're here, because today we are diving into one of the most dramatic, complex, and genuinely fascinating topics in the entire OCR specification — the Aztecs and the Spanish Conquest, covering the period 1519 to 1535. Whether you're revising for the first time or doing a final polish before your exam, this episode is going to walk you through everything you need to know. We'll cover the core concepts, the key events, the individuals who shaped history, and crucially — the exam technique that will get you those top marks. By the end of this episode, you'll understand why a small group of Spanish conquistadors, numbering just a few hundred, managed to bring down one of the most powerful empires in the Americas. So let's get started. Grab your revision notes, and let's go back to 1519. CORE CONCEPTS (approx. 5 mins) Section One: The Aztec Empire Before the Conquest. By 1519, the Aztec Empire — also known as the Triple Alliance — controlled much of central Mexico. Its capital, Tenochtitlan, sat on an island in Lake Texcoco and had a population of somewhere between 200,000 and 300,000 people. That made it larger than any city in Europe at the time. The city was connected to the mainland by three great causeways and fed by chinampas — floating gardens. The empire was ruled by a tlatoani. In 1519, that ruler was Moctezuma II. He governed through a system of tribute — this tribute system was both the empire's greatest strength and one of its fatal weaknesses. The Aztecs believed that human sacrifice was necessary to feed the sun god Huitzilopochtli and prevent the destruction of the world — a cosmic obligation that also served to demonstrate political power and keep subject peoples in fear. Section Two: The Arrival of Cortés, 1519. In February 1519, Hernán Cortés landed on the coast of Mexico with approximately 500 soldiers, 16 horses, and a small number of cannons. Cortés had a crucial advantage: a translator — La Malinche, also known as Doña Marina — a Nahuatl-speaking indigenous woman who enabled him to identify which peoples resented Aztec rule. The Tlaxcalans — a people who had resisted Aztec domination — allied with Cortés after initially fighting him. By the time Cortés marched on Tenochtitlan, his total allied force numbered over 200,000 warriors. This is absolutely critical for your exam: the conquest was not a Spanish military victory alone. It was a coalition war. Cortés entered Tenochtitlan in November 1519 and took Moctezuma hostage within the city. Section Three: The Noche Triste and the Smallpox Epidemic, 1520. In June 1520, while Cortés was away, his lieutenant Pedro de Alvarado massacred Aztec nobles at a religious festival. The city erupted in revolt. Moctezuma was killed. The Spanish were driven out on the night of 30th June 1520 — the Noche Triste, the Night of Sorrows. But here is where biology changed history. Smallpox had arrived in Mexico with the Spanish in 1520. The Aztec population had no immunity. The epidemic killed perhaps a third to a half of Tenochtitlan's population and killed the new emperor Cuitlahuac just 80 days into his reign, creating a catastrophic leadership vacuum. Section Four: The Siege and Fall of Tenochtitlan, 1521. Cortés regrouped and had thirteen brigantines constructed and transported overland to Lake Texcoco, giving the Spanish control of the lake. The siege began in May 1521 and lasted 75 days. The last Aztec emperor, Cuauhtémoc, was captured on 13th August 1521. Tenochtitlan was in ruins. On its rubble, the Spanish built Mexico City. Section Five: The Establishment of New Spain, 1522–1535. Cortés was appointed Governor of New Spain in 1522. The encomienda system was established — a grant of indigenous labour to Spanish colonists, supposed to involve protection and Christianisation but in practice a system of brutal exploitation. By 1535, New Spain was formally established as a viceroyalty. EXAM TIPS AND COMMON MISTAKES (approx. 2 mins) For the inference question: use the formula 'I can infer X... The source suggests this by showing Y.' Do this twice. For the 12-mark Explain Why question: structure around three distinct factors using PEEL — Point, Evidence, Explanation, Link. For the 25-mark essay: sustain an argument, weigh factors, and make a clear judgement in your conclusion. Common mistakes: conflating 1519 with 1521; underestimating the Tlaxcalans; calling the encomienda system simply 'slavery'; failing to use precise terminology like chinampas, Noche Triste, brigantines, tlatoani, and encomienda. QUICK-FIRE RECALL QUIZ (approx. 1 min) Q1: Cortés's translator? La Malinche / Doña Marina. Q2: Noche Triste? Night of Sorrows, 30th June 1520. Q3: Last Aztec emperor? Cuauhtémoc. Q4: Chinampas? Floating gardens. Q5: Encomienda? Spanish colonial labour grant system. SUMMARY AND SIGN-OFF (approx. 1 min) The fall of the Aztec Empire resulted from multiple converging factors: Spanish military technology, the Tlaxcalan alliance, the smallpox epidemic, Aztec internal divisions, and the leadership of Cortés. The consequences — New Spain, the encomienda system, and the deaths of millions — were profound and long-lasting. Be specific, be analytical, always link your evidence to the question. You've got this. Good luck!
Key Terms & Definitions
- Tlatoani
- The supreme ruler of the Aztec Empire, literally meaning 'he who speaks' in Nahuatl. The tlatoani held both political and religious authority, acting as intermediary between the people and the gods.
- Chinampas
- Artificial islands constructed in the shallow waters of Lake Texcoco, used for intensive agriculture. Built by layering mud, aquatic vegetation, and soil, chinampas were anchored by willow trees and could be highly productive.
- Encomienda
- A Spanish colonial labour grant system in which the Crown assigned a number of indigenous people to a Spanish colonist (the encomendero). The encomendero was theoretically obliged to provide protection and Christian instruction; in practice, the system enabled brutal exploitation of indigenous labour.
- Noche Triste
- Literally 'Night of Sorrows' — the night of 30 June 1520 when the Spanish and their allies were driven out of Tenochtitlan by Aztec forces following Pedro de Alvarado's massacre of Aztec nobles. Hundreds of Spanish soldiers drowned in Lake Texcoco.
- Brigantines
- Flat-bottomed warships constructed by Cortés and transported overland in pieces to Lake Texcoco in 1521. The thirteen brigantines gave the Spanish naval control of the lake during the siege of Tenochtitlan, cutting off the city's supply lines.
- Triple Alliance
- The political and military alliance of the three city-states of Tenochtitlan, Texcoco, and Tlacopan that formed the basis of the Aztec Empire. Tenochtitlan was the dominant partner, receiving the largest share of tribute.
- Macuahuitl
- The primary Aztec weapon — a wooden club edged with sharp obsidian blades. Highly effective against other Mesoamerican warriors, but unable to penetrate Spanish steel armour.
- Viceroyalty
- A colonial territory governed by a viceroy — a representative of the Spanish Crown — with full administrative, judicial, and military authority. New Spain became a formal viceroyalty in 1535 under the first Viceroy, Antonio de Mendoza.
- Tribute System
- The mechanism by which the Aztec Empire extracted wealth from conquered peoples. Subject cities were required to pay regular tribute in goods (textiles, cacao, gold, feathers), labour, and sacrificial victims to Tenochtitlan.
Worked Examples
Worked Example
Question: Explain why the Spanish were able to conquer the Aztec Empire by 1521. (12 marks)
Solution: **Introduction**: The Spanish conquest of the Aztec Empire by 1521 was the result of several interconnected factors, including Spanish military technology, the critical alliance with the Tlaxcalans, and the devastating impact of the smallpox epidemic. No single factor alone was sufficient; it was their combination that proved fatal to the Aztec Empire. **Paragraph 1 — The Tlaxcalan Alliance**: The most important factor enabling the conquest was the alliance Cortés forged with the Tlaxcalans in 1519. The Tlaxcalans were a people who had successfully resisted Aztec domination and deeply resented the tribute demands and human sacrifices imposed by the empire. After initial fighting, Cortés negotiated an alliance, and by the time he besieged Tenochtitlan in 1521, his force included an estimated 50,000–200,000 Tlaxcalan warriors alongside just a few hundred Spanish soldiers. This alliance was decisive because it provided the military manpower that the Spanish alone could never have supplied. Without the Tlaxcalans, the siege of Tenochtitlan — a city of 200,000–300,000 people connected to the mainland by three causeways — would have been impossible. The alliance was itself made possible by the Aztec tribute system, which had created widespread resentment among subject peoples — demonstrating how the empire's internal divisions were a precondition for the conquest. **Paragraph 2 — The Smallpox Epidemic**: A second crucial factor was the smallpox epidemic that swept through Tenochtitlan from 1520 onwards. The Aztec population had no prior exposure to European diseases and therefore no immunity. The epidemic killed an estimated one-third to one-half of the city's population. Crucially, it killed Emperor Cuitlahuac — who had led the forces that drove the Spanish out during the Noche Triste — just 80 days into his reign. This created a catastrophic leadership vacuum at the moment when the Aztecs most needed strong, unified command. Smallpox also destroyed the morale of the defenders: the Aztecs interpreted the epidemic as a sign of divine abandonment, undermining the religious and psychological foundations of their resistance. This demonstrates how biological factors combined with political and psychological consequences to weaken Aztec defence. **Paragraph 3 — Spanish Military Technology and Leadership**: Spanish military technology provided Cortés with a decisive tactical advantage. Steel swords, armour, and crossbows were superior to Aztec obsidian-edged weapons (macuahuitl). Horses — entirely unknown in the Americas — caused terror among Aztec warriors who had never encountered them. Most significantly, Cortés had thirteen brigantines constructed and transported overland to Lake Texcoco in 1521. These flat-bottomed warships gave the Spanish control of the lake, cutting off Tenochtitlan's supply lines and preventing resupply or escape. This logistical masterstroke, combined with Cortés's strategic intelligence and willingness to take extreme risks, turned the siege into a systematic destruction of the city. **Conclusion**: The conquest succeeded because these three factors reinforced each other. Spanish military technology alone could not have overcome a city of hundreds of thousands; the Tlaxcalan alliance provided the necessary manpower. The alliance was possible because Aztec internal divisions had created willing enemies of the empire. And smallpox removed the leadership and morale that might otherwise have sustained Aztec resistance. Of these factors, the Tlaxcalan alliance was arguably most important, since without indigenous military support, the Spanish could not have prosecuted the siege at all — but it was the combination of all three that made the conquest inevitable by 1521.
Worked Example
Question: Study Source A [a Spanish colonial illustration showing Aztec warriors in battle dress]. What can you infer from Source A about the Aztec military? (3 marks)
Solution: **Inference 1**: I can infer from Source A that warfare held a central and prestigious place in Aztec society. The source suggests this by depicting warriors in elaborate ceremonial battle dress, including feathered headdresses and jaguar-skin armour, indicating that military rank and achievement were publicly displayed and socially valued. **Inference 2**: I can also infer that the Aztecs used warfare not only for conquest but for the capture of prisoners. The source suggests this by showing warriors wielding macuahuitl (obsidian-edged clubs) designed to wound and incapacitate rather than kill outright, consistent with the Aztec practice of taking prisoners for ritual sacrifice rather than killing enemies on the battlefield.
Worked Example
Question: How useful are Sources A and B for an enquiry into the reasons why the Aztec Empire fell to the Spanish? (8 marks)
Solution: **Source A Analysis**: Source A is useful for this enquiry because its content reveals the nature of Aztec warfare, showing warriors equipped with obsidian-edged weapons and elaborate ceremonial armour. This helps explain why the Aztecs were militarily vulnerable to the Spanish: their weapons, while effective against other Mesoamerican peoples, were inferior to Spanish steel. The provenance of Source A — a Spanish colonial illustration produced after the conquest — adds to its usefulness in one respect: Spanish artists had direct knowledge of Aztec military practices from the conquest itself. However, its usefulness is limited by its provenance: as a post-conquest Spanish production, it may exaggerate Aztec 'otherness' or ferocity to justify the conquest, potentially distorting our understanding of Aztec military capability. **Source B Analysis**: Source B [a passage from Bernal Díaz del Castillo's account of the Tlatelolco market] is useful because its content demonstrates the sophistication and wealth of Aztec civilisation, which helps explain why the Spanish were motivated to conquer it. Díaz's description of a market larger than any in Spain suggests the enormous economic resources of the empire. The provenance — an eyewitness account by a Spanish soldier who participated in the conquest — gives it high value for understanding what the Spanish encountered. However, Díaz wrote his account decades after the events, meaning his memory may have been shaped by subsequent experiences, and as a participant in the conquest, he had a personal interest in emphasising the grandeur of what was conquered. **Comparison and Judgement**: Overall, Source B is more useful for this specific enquiry because it directly addresses the motivations for conquest — the wealth and sophistication of the Aztec Empire — whereas Source A addresses military practices more narrowly. However, both sources are limited by their Spanish perspective: neither provides insight into Aztec internal divisions or the role of the Tlaxcalan alliance, which were arguably the most important reasons for the empire's fall.
Worked Example
Question: 'The smallpox epidemic was the most important reason why the Aztec Empire fell to the Spanish.' How far do you agree with this statement? (25 marks)
Solution: **Introduction**: The smallpox epidemic of 1520 was undoubtedly a significant factor in the fall of the Aztec Empire, killing an estimated one-third to one-half of Tenochtitlan's population and crucially removing Emperor Cuitlahuac from power after just 80 days. However, to argue that it was the single most important reason oversimplifies a complex causal picture. The Tlaxcalan alliance, Aztec internal divisions, and Spanish military technology were equally or more fundamental — and without them, the epidemic alone would not have been sufficient to bring down the empire. **Argument in favour — Smallpox was decisive**: The case for smallpox as the most important factor rests on its unique and irreplaceable contribution. No other factor so fundamentally altered the balance of power between the two sides. The epidemic killed Cuitlahuac — the very emperor who had successfully driven the Spanish out during the Noche Triste of June 1520 — creating a leadership vacuum at the most critical moment. It reduced the population of Tenochtitlan by perhaps 30–50%, directly weakening the city's capacity to resist the siege of 1521. It also had a profound psychological impact: the Aztecs interpreted the epidemic as a sign of divine abandonment, undermining the religious foundations of their resistance. Without smallpox, the Aztecs might well have repelled the Spanish entirely after the Noche Triste. **Counter-argument — The Tlaxcalan alliance was more important**: However, the Tlaxcalan alliance was arguably the more fundamental factor, because without it, the Spanish could not have prosecuted the siege regardless of the epidemic's impact. Cortés arrived in Mexico with approximately 500 soldiers — a force wholly inadequate to besiege a city of 200,000–300,000 people connected to the mainland by three causeways. The Tlaxcalans provided an estimated 50,000–200,000 warriors, the military mass without which the siege was impossible. The alliance was itself a product of Aztec internal divisions — the resentment created by decades of tribute extraction and forced human sacrifice. This suggests that the structural weakness of the Aztec Empire, not the contingent arrival of disease, was the most fundamental cause of its fall. **Additional factor — Spanish military technology**: Spanish military technology also played an important role, particularly the thirteen brigantines that Cortés had constructed and transported overland to Lake Texcoco in 1521. These gave the Spanish control of the lake, cutting off Tenochtitlan's supply lines and making the siege viable. Steel weapons and horses provided tactical advantages in open battle. However, technology alone could not overcome a city of hundreds of thousands — it was an enabling factor rather than a primary cause. **Conclusion**: Smallpox was a necessary but not sufficient cause of the Aztec Empire's fall. Without the epidemic, the conquest would have been far more difficult or even impossible. But the Tlaxcalan alliance was the more important factor overall, because it provided the military manpower without which the siege could not have been conducted. The epidemic accelerated and enabled the conquest; the alliance made it possible in the first place. The most accurate explanation recognises that it was the combination of all these factors — internal Aztec divisions, indigenous alliances, epidemic disease, and Spanish technology — that together produced the conquest, with no single factor sufficient on its own.
Worked Example
Question: Describe two features of the Aztec city of Tenochtitlan. (4 marks)
Solution: **Feature 1**: One feature of Tenochtitlan was its extraordinary size and population. The city was built on an island in Lake Texcoco and had a population of approximately 200,000–300,000 people, making it larger than any contemporary European city, including London and Madrid. This scale reflected the wealth and power of the Aztec Empire. **Feature 2**: A second feature was the system of chinampas — floating gardens — that surrounded the city. These were artificial islands constructed in the shallow lake, used to grow crops such as maize, beans, and squash. The chinampas were a sophisticated agricultural innovation that allowed Tenochtitlan to feed its enormous population despite being situated on a lake.
Practice Questions
Question: Explain why the Tlaxcalan alliance was important in the Spanish conquest of the Aztec Empire. (12 marks)
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Question: Describe two features of the encomienda system established in New Spain after 1522. (4 marks)
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Question: 'Smallpox was the main reason why the Spanish were able to conquer the Aztec Empire.' How far do you agree with this statement? (25 marks)
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Question: What can you infer from a source showing Aztec warriors performing human sacrifice at the Templo Mayor? (3 marks)
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Question: Explain why Cortés was able to enter Tenochtitlan peacefully in November 1519. (12 marks)
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