In 1519 the maverick conquistador rallied from near-certain annihilation to victory over the Aztec Empire—thanks to an earlier defeat at the hands of the Aztecs’ rivals, the Tlaxcaltecs.

Hernán Cortés marched boldly toward Tlaxcala in late August 1519, brimming with confidence. Since landing in Yucatán that spring, success had followed success. He had defeated a Maya army; demonstrated his cavalry and artillery to cow  Aztecs along the Gulf Coast; allied with Cempoala, a Totonac city chafing under Aztec domination; and bullied another fortified Totonac city into submission.

Now he had made an irreversible decision. Rebelliously ignoring the orders of his patron, Cuban Governor Diego Velázquez, he founded Vera Cruz (north of modern-day Veracruz) and appointed a city council that authorized an inland expedition. To prevent desertions, he scuttled his ships and punished those agitating to return to Cuba. Leaving his wounded and infirm at Vera Cruz with six Lombard cannons, he marched inland.

With a force of 300 Spaniards, 50 Totonac warriors and 17 horses, Cortés headed toward the Aztec capital of Tenochtitlán (now Mexico City). As preColumbian Mexico had neither wheeled vehicles nor draft animals, 200 porters carried equipment and supplies.

Climbing onto the central plateau, they marched for two weeks, being received and fed by the towns en route, including Aztec tributaries, until they neared Tlaxcala. Cortés knew Tlaxcala opposed the Aztecs, but he was unsure of his own reception. The matter was clarified when he spotted a small party of Indians and sent horsemen to capture them.

To the Spaniards’ surprise, the Tlaxcaltecs fought back, wounding two men and three horses and killing two other horses before fleeing. Their resistance and effectiveness confounded Cortés’ prior experiences, which he had profoundly misinterpreted. He hadn’t realized most of the Maya army he defeated wasn’t a professional force, but consisted of conscripted commoners supporting a small cadre of trained elites. Cortés had also underestimated the Aztecs, who had only refused battle by royal order, and he had overestimated his Totonac allies, who were not especially warlike. His errors were exposed in this brief clash, Cortés’ first against trained indigenous soldiers. The small party of Tlaxcaltecs was a test of Spanish intentions that Cortés failed when he attacked.

His horsemen repulsed, Cortés brought up his main force, armed with swords, pikes, crossbows and harquebuses (matchlock muskets) and supported by mounted lancers and falconets (light cannons), all unknown in Mexico. In virtually every category Spanish arms were superior, pitting iron and steel against wood and stone, supported by the speed and power of cavalry.

In seeming retreat, the Tlaxcaltecs drew the Spaniards forward. When Cortés’ men were exposed, a concealed Tlaxcaltec army some 3,000 strong suddenly attacked.

Cortés was justly confident of his men, though whether they actually faced a 6-to-1 disadvantage is uncertain. These and other recorded numbers are approximations at best; they differ among the self-serving accounts of the conquistadors, who exaggerated both deeds and obstacles in hopes of receiving lands and money from the Spanish crown. Even more exaggerated, the Spaniards claimed a kill ratio of 20- or 25-to-1. If true, Cortés would have triumphed, and Spanish arms would have proven decisive. Although steel blades retained their edges, and swords and pikes were used to thrust as well as slash, Indian arms were not wholly overmatched. Their wooden broadswords and thrusting spears could only slash, but their obsidian blades were sharper than steel. Indeed, twice in the battle, Indians reportedly decapitated horses with a single stroke. And though obsidian blades were fragile, they could be replaced quickly.

Tlaxcaltec soldiers were well trained and disciplined. In the battle they soon overwhelmed the Spaniards, forcing them into a defensive posture. Cortés’ men held on until dusk, when the fight ended. For 17 Tlaxcaltecs claimed killed, four Spaniards had been seriously wounded, one mortally, and two horses were dead.

Spanish armor proved effective against Tlaxcaltec arms, keeping casualties low. But while most conquistadors had helmets, few could afford plate armor and instead wore an eclectic assortment of plate, mail and leather. Thus a disproportionate number of Spanish casualties were from wounds to unprotected areas—face, neck and chest via neck and arm openings in the armor.

Cortés regrouped. He feared using his cavalry, as he had only 13 horses left, some wounded, and dared not risk them in unsupported forays. Projectiles would prove his most effective weapon.

Projectiles weren’t a Spanish monopoly. Tlaxcaltec atlatls could throw darts more than 150 feet and were most effective when closing with the enemy. Their bows had a range between 300 and 600 feet, a distance their slings doubled. Distance and terrain features, however, obscured targets, limiting accuracy and effect of all weapons.

Spanish armor was effective at a distance, though even plate armor was not proof against atlatl darts at close range. Arrows were a problem as well. They may not have penetrated, but stone points often shattered on impact against breastplates, spraying fragments into the wearers’ eyes. And against mail, reed shafts split on impact, sending slivers through the mesh. The effectiveness of Spanish armor improved the farther at bay the Indians were kept.

Military crossbows could shoot a 1.5- to 3-ounce bolt more than 200 feet point blank. Harquebuses had a similar pointblank range with a 2- to 6-ounce ball, but half the crossbows’ maximum. Falconets boasted the greatest range: nearly 500 feet point blank and more than a mile maximum for a 2- to 10-pound ball.

Tlaxcaltec armor offered some protection. It consisted of quilted cotton, 2 to 3 inches thick, in jerkins that left the limbs unencumbered. Though light, cotton armor absorbed blows and slashes so effectively that many Spaniards later adopted it in preference to their own. Nevertheless, cotton armor wasn’t proof against the greater impact of Spanish projectiles, especially at close range.

The Spaniards, though battered, survived this initial battle with the Tlaxcaltec warriors. Withdrawal, Cortés’ best option, was politically impossible. His actions in defiance of Velázquez’s orders meant probable execution. Showing weakness would also alienate his Totonac allies and likely invite Aztec retaliation. Given such bleak choices, Cortés chose to remain in position, facing the Tlaxcaltecs.

An even larger Tlaxcaltec force attacked the Spaniards the following day, keeping them on the defensive.

Indigenous battles usually opened with an arrow and slingstone barrage at about 200 feet, covering the approach of frontline fighters, who wielded atlatls as they advanced. Once in contact, fighting shifted to the more effective broadswords and thrusting spears.

But since the Spaniards didn’t advance to meet them, it took the Tlaxcaltecs twice as long to close. All the while, Spanish fire tore into their formations, eventually driving back the assault.

Elated, the Spaniards charged after the fleeing Tlaxcaltecs, only to find themselves drawn into another ambush, surrounded and assailed from all sides. Again on the defensive, Cortés used his firepower to force a Tlaxcaltec withdrawal. During this brief respite, the Spaniards retreated to more defensible buildings nearby, having lost one dead, 15 wounded and four or five additional horses killed.

Though the wounded far outnumbered the killed in these battles, the consequences of a wound could be dire. Wounds to limbs or muscle tissue were rarely fatal. Both the Spaniards and Tlaxcaltecs set bones and sutured wounds, and both applied medicinal salves. But neither could effectively repair internal damage. Punctures of the abdominal cavity that damaged internal organs or introduced infections were virtual death sentences. And projectiles that caused such punctures were common in these fights.

In two days of combat, the Tlaxcaltecs hadn’t overrun the Spanish defenses, but neither had the Spaniards prevailed. It was a stalemate, but the advantage lay with the Tlaxcaltecs, who could secure additional men and supplies. Cortés’ position was more precarious. Over two days, the Spaniards had suffered at least two killed, perhaps 20 wounded, and lost at least six horses. Neither men nor horses were replaceable. Supplies were dwindling. The Spaniards had been resupplying at towns along their route, but that ended abruptly in Tlaxcaltec territory.

The next day brought another Tlaxcaltec attack. Their massive frontal assault began conventionally, and Cortés again concentrated on keeping them at bay. Using half his men to reload crossbows and harquebuses while the best shots fired, Cortés increased the overall rate of fire and forced the Tlaxcaltecs back beyond the effective range of their own arms. Once again the Spaniards staved off defeat, but at the cost of another man killed and 60 men and all remaining horses wounded. While the attacks were grinding the Spaniards down, the Tlaxcaltecs also suffered significant losses, as the Spanish arms commanded a larger killing zone. The next Tlaxcaltec ploy sought to remove that advantage.

Night attacks were rare in Mexico, typically employed only in raids. Initiated by drums or trumpets, battles usually began at dawn to maximize daylight. Audible commands were ineffectual over the din of battle. Instead, standards were used as visual signals. Strapped to the leaders’ backs, these light feather-and-cane insignias towered overhead and guided their respective units. But standards weren’t visible at night, nor could leaders use audible commands without sacrificing surprise.

In the face of superior Spanish firepower, however, the Tlaxcaltecs decided to take their chances. While the darkness would impede their own maneuvers and communications, the Spaniards would be similarly handicapped, as they couldn’t see to take advantage of their weapons’ greater ranges.

Spanish crossbows, harquebuses and falconets all fired at slower rates than Tlaxcaltec projectiles. Harquebuses required about 1l⁄2 minutes to load, prime and fire; crossbows took about a minute. Surprisingly, falconets were ready to fire in about half a minute, as they were breechloaders.

But even these slow rates of fire weren’t sustainable. Spanish arms were heavy, crossbows weighing about 15 pounds and harquebuses 2 to 5 pounds more. Soldiers’ arms quickly tired, becoming unsteady after half an hour’s fire.

Darkness hardly slowed Tlaxcaltec fire at all. Their arms were lighter and simpler to use, and they knew precisely where the Spaniards stood, immobile behind their defenses. In the absence of effective Spanish fire to keep them far enough back, the Tlaxcaltecs could exploit these higher rates of fire.

Though atlatls were shorter-range weapons, they could throw darts quickly, on a par with bows and slings, about six times per minute. Arrows were especially effective in volleys, as archers could be massed closer together than slingers. Yet slingers proved more effective against Spanish armor, because stones injured on impact, not penetration.

The Tlaxcaltecs’ night assault was launched from all directions at once. Archers, slingers and atlatlists remained stationary, assailing the Spaniards on three sides, while Tlaxcaltec swordsmen attacked from the fourth. Darkness had granted the Spaniards one advantage, however; their horsemen were able to counterattack without infantry support. The Tlaxcaltec attack on that side collapsed.

Nevertheless, 50 of Cortés’ 300 men were dead, most of the rest were wounded, and a dozen were ill. Food supplies were dwindling and, even more critical, so too were armaments, which could not be replenished in the field.

At one shot per minute per crossbow, an hour’s combat for all 32 crossbowmen translated to 200 to 350 pounds of expended bolts. Similarly, at one shot every one and a half minutes, the 15 harquebuses expended 600 two-ounce balls and an equal weight of gunpowder, or 130 pounds, and the four falconets expended 60 to 200 pounds of ammunition per hour. At these rates, each hour of vigorous combat with all weapons consumed 400 to 700 pounds of irreplaceable armaments. Just how many bolts, rounds, shot and gunpowder Cortés brought is not recorded, but Totonac porters toted all the armaments, and only 200 accompanied the expedition. The porters also had to carry food.

The party that left the Yucatán coast numbered 550 men, counting the Totonac warriors and porters, and the daily ration was more than two pounds of maize. At least half of the porters accompanying Cortés carried food, which at the conventional load of 50 pounds per porter meant 5,000 pounds of maize.

If the remaining 100 porters did carry bolts, rounds, shot and gunpowder alone (ignoring the four falconets, which jointly weighed at least 2,000 pounds and required litters employing some 40 porters), their collective weight meant the porters could only carry enough for seven to 12 hours of vigorous combat.

Cortés’ position was desperate. He continued to dispatch parties to nearby towns in search of food, but managed to sack only one, with fleeting benefit. Many of his men were near mutiny, openly demanding a return to the coast. By every measure but death, Cortés was defeated, and even death required no further Tlaxcaltec attacks, only a brief encirclement. He was simply incapable of defeating the Tlaxcaltecs, much less the powerful Aztecs.

Yet in less than two years, Cortés would stand in the ruins of Tenochtitlán and accept the Aztec surrender. How did he manage such a miraculous turnaround?

The answer lay with the Tlaxcaltecs. Had they decided to continue this battle and crush the Spaniards, Cortés would have been just another failed adventurer. But in a surprising decision based on geopolitics and domestic rivalries, Tlaxcala gave the Spaniards a reprieve.

In 1519 the Aztecs dominated the region. From their rise in 1428, they had extended their empire across most of central Mexico. Some cities allied with the empire, but more were conquered or intimidated into submission by the might of the Aztecs and their allies. The empire marshaled many tens of thousands of soldiers and dispatched them over vast distances. The soldiers were the best in Mexico, the product of schools that trained both commoners and nobles.

Yet independent, even hostile, states still existed, notably the Tlaxcaltec confederacy. These polities remained free not because they couldn’t be conquered, but because of the costs involved. The Aztecs conquered many distant states, but did not—and could not—control them all directly. Such control would mire their army in garrison duty. Instead, they left existing rulers in control, as long as they complied with Aztec demands. Tributaries paid tribute, but weren’t otherwise integrated into the empire. So it wasn’t caprice that left some polities unconquered. Distance was a factor, but relative military strength loomed larger.

Aztec conquests were motivated in large part by the need for tribute. The king possessed great but not absolute power: Chosen by and from the upper nobles (lords), he ultimately depended on their support, which required a continued and expanded influx of tribute to support king and lords. That, in turn, required continued expansion.

City-states in the region were relatively easy conquests. They rarely controlled more than an eight-mile radius—too small to afford protection from Aztec armies. Marching with their own supplies, the Aztecs could reach a city and defeat its army or intimidate its leaders into surrender.

On the other hand, confederacies and empires possessed larger armies and, more important, controlled larger territories. While these expanses remained vulnerable to attack, they also afforded a buffer, thanks to the Mesoamerican Achilles’ heel: logistics.

Narrow roads and the dynamics of marching meant each Aztec army of 8,000 men (a xiquipilli) averaged just 12 miles per day, comparable to distances traveled by preindustrial armies elsewhere. The best-supplied armies employed only one porter for every two soldiers, carrying just eight days of food for all three. Eight days meant the Aztecs could reliably march three days to their target, fight one day (usual against city-states), recuperate one day, then march back three days without resupply, for a combat radius of only 36 miles. Multiple xiquipillis could be dispatched on parallel routes simultaneously, but on single routes only one xiquipilli could leave per day. Each additional xiquipilli added another day at the assembly point, correspondingly reducing supplies. To expand their range, the Aztecs demanded food from their tributaries en route, thereby enabling their armies to strike hundreds of miles away.

This strategy lacked effect against confederacies and other empires. They could meet Aztec incursions at their borders, and defeat there meant only the loss of a peripheral area. A vanquished army could withdraw into its territory, where the Aztecs had no logistical support and couldn’t follow.

To conquer a confederacy or empire required a protracted effort over many years, further complicated by several factors. First, such undertakings promised few immediate returns—the whole point of conquest. They also diverted forces that could be employed to conquer easier tribute-paying targets elsewhere. And unless such campaigns were consistently successful, the Aztecs might appear weak and encourage rebellion by other tributaries. Even in a successful campaign, if the Aztecs were badly mauled, their authority would be thrown into doubt.

Rather than squander their army in protracted campaigns, the Aztecs engaged confederacies and empires in gradual and progressive intimidation with limited troops, freeing the main forces for warfare elsewhere, including along their enemies’ peripheral territory. Subduing complex polities became a lengthy process of gradual encirclement. The Aztecs would cut them off from allies and chip away at the edges until they could be crushed outright.

Tlaxcala had been engaged in such a conflict with the empire for nearly six decades, first as a partner to Huexotzinco and Atlixco before becoming the primary target over the past few decades. And that lengthy war was going against it.

One nearby major ally had been conquered; another had simply defected to the Aztecs. And while Huexotzinco was allied with Tlaxcala against the Spaniards, it was an unreliable partner; Huexotzinco had become an Aztec ally in 1512 and only became re-allied with Tlaxcala in 1517. Though still independent, Tlaxcala was encircled, watching its allies fall one by one.

In most Mexican states and empires, power was concentrated in a single leader whose political decisions were widely supported. By contrast, Tlaxcala was a confederacy of four provinces ruled jointly by four kings, so decisions weren’t monolithic and often masked significant divisions. Changing circumstances often led to abrupt, even contradictory, changes.

Two rulers—Xicoténcatl the Elder and Maxixcatl—vied for dominance. Xicoténcatl prevailed in urging that they fight Cortés, but Maxixcatl would benefit if he failed, particularly since his son, Xicoténcatl the Younger, commanded the army.

Thus after a few desperate days of battle, support swung to Maxixcatl, and the Tlaxcaltec council ordered the fighting halted. At first Xicoténcatl the Younger ignored the order, knowing if he persisted and won, his political status would improve. But when Maxixcatl withdrew his army, Xicoténcatl’s final daytime attack was doomed, forcing him to withdraw his own warriors.

Regardless of this internal power struggle, continued Aztec encroachment presented an even greater reason to halt the fighting. Encircled and beleaguered, Tlaxcala was perhaps no more than two decades from wholesale defeat by the Aztecs. The end appeared inevitable, and defeat of Cortés’ conquistadors would not improve their predicament.

It has long been conventional wisdom to attribute the Spanish conquest of Mexico to superior leadership, tactics or arms, but that is inaccurate. The Tlaxcaltecs simply realized that Spanish arms could achieve the one thing theirs could not: conquest of the Aztec Empire.

In indigenous warfare, maintaining a cohesive front was crucial, allowing combatants to focus on the enemy before them without concern for their sides or rear. Victory was usually achieved by disrupting the opposing line, pouring through en masse and turning its flanks. This was difficult, as both sides used the same weapons and tactics. The larger force almost always won, as it could extend its front much farther than its opponent. It was exceptionally difficult for equal or smaller forces to make such a breakthrough.

But in their clashes with the Spaniards, the Tlaxcaltecs had noted how effective falconets, harquebuses and crossbows were in breaking up their ranks. Unable to maintain formation in the face of Spanish fire, they couldn’t sustain their attacks despite superior numbers. The Spaniards were too few to exploit this advantage, but the Tlaxcaltecs recognized the tactical implications for their own army and acted on that insight.

By allying with Cortés, the Tlaxcaltecs could use the surviving 250 Spaniards with their weapons as shock troops to punch through enemy lines, enabling Tlaxcaltec troops to pour through and attack their opponents’ vulnerable flanks. Such an alliance would tip the regional balance of military power in Tlaxcala’s favor, even against superior numbers.

If Cortés recognized this advantage, he was helpless to implement it on his own, despite his many boasts. Only the Tlaxcaltecs could halt the attack on the Spaniards. Only they could initiate an alliance.

During the ensuing conquest of Mexico, additional landings brought more Spaniards, multiplying their number perhaps eightfold (about half survived), but they were never anywhere near a majority force. In the end they comprised no more than 1 percent of the forces arrayed against the Aztecs. The conquest was a Tlaxcaltec victory for which the Spaniards took credit.

Even in the final battles, the Aztecs would unhesitatingly attack Indian formations. The Tlaxcaltecs exploited that approach by dressing a few Spaniards as Indians and concealing them in their midst until the Aztecs were committed. Then the Spaniards would bring their arms to bear, disrupting the attackers and securing Tlaxcaltec victory.

The strategy was a stunning success. Tenochtitlán fell two years later, on August 13, 1521.


For further reading, pick up copies of Mexico and the Spanish Conquest and Aztec Warfare: Imperial Expansion and Political Control, both by Ross Hassig

Originally published in the May 2007 issue of Military History. To subscribe, click here