Why did the Incas and Aztecs succumb to the Spanish so easily?

You can answer the question quickly, saying "technology". However, everyone knows that. A detailed and original discussion is still possible.

So, why did the Incas and Aztecs succumb to the Spanish so easily?

one reason is they were both so centrally organized that when the spanish took there leaders they were unable to act. a powerful body with no head to think or guide it.

Didn't the Spanish also ally with many of the neighboring civilizations to fight the Aztecs. Many people wanted to see them gone.

Smallpox also helped...

Also, Aztec warriors were equipped with weapons designed not to kill, but to enslave...

Guns, Germs, and Steel

this is bot a cheap answer, and a book you need to read, as it answers this exact question, and gives all the reasons why what led upto it, led up up to ti, from what Native americans werent as advanced 9lack of good domesticate sto begin an argicultural, and completelly sedentry soceity), to eveythign else that coudl possibly be conencted with the question.

Tech (obviously), Disease, Centralized chain of command, Native Allies, shock and awe.

In terms of religious conversion, many people were led to believe that their gods were the same as the christian Saints. When they are christian it only takes a few generations to get them converted.

Remember that the Aztecs and Incas were both empires, and empires are comprised of many oppressed nations and these nations eagerly allied themselves with the Spanish because they were tired of paying tribute. Of course the Spanish turned out to be just about as bad, but they didn't know it at the time. Disease and technology also played their roles too, of course.

Everything mentioned here makes sense, and Zen; my compliments for a great book recommendation, "Guns, germs and steel" by Jared Diamond is very interesting reading indeed.
The crucial meeting was of course the first, that between the Spanish and the Aztecs. We should not forget that the outcome of this confrontaton could have ended differently.
It is true that the Spanish had a great technological advantage, but one should also consider that the Aztecs disposed over a organized, experienced army vastly superior in numbers.
Interestingly the Spanish and Aztecs showed a great similarity in many ways. Both were very militaristic, convinced that their mission in the world was to rule it, worshipping heroicism and willing to kill - a lot - for their empire, their ruler, their god. Both nations were also comparatively young, and had risen to power by supressing and exploiting other people.
The Aztec empire had two weaknesses. Because of theirr cruelty and greed, they were hated by neighbours and feared by clients. This made it easy for the Spanish to find allies. Besides their religion, rigid and fatalistic, made them look at the world in a manner that forced them to interpret the Spanish in a certain predestined way.
It is an old cliche that truth is stranger than fiction and the embarking of Cortez and his men is an example of that. One of the religious stories of the Aztecs was about the god Quetzalcoatl who should return and haunt the Aztecs dressed in black on a certain date. It so happened that the day of Cortez' arrival corresponded exactly with the date of the Aztec calendar and - since it was Long Friday he was wearing black... To put it mildly, this made the occupation of Tenochtitlan easier.
In any case, reality eventually kicked in, and as we all know, following Spanish atrocities, an Aztec upheaval was successful, Cortez and what was remaining of his army had to retreat.Here he could have been history (Couldn't resist this pun! ).
Not so. Because as other posters already pointed out, smallpox made its appearance, and instead of being thrown at the sea, the Spaniards could get their act together and prepare for another invation of a weakened empire. On top of that, the fact that Aztec religion regarded skin diseases as a punishment from the gods, and that the whites did not get it, can't hardly have boasted the moral.
Now the Meso-American civilizations would probably have ended up under European domination anyway. For the real great technological advantage the Europeans disposed of was their ships - if one attempt failed one could relatively easily try again. But they would also probably survived, and the world could have looked differently.
I apologize for the rather messy disposition of this post, it is mainly based on notes of a lecture I held some time ago based on different sources, but I hope some people find it interesting anyway.

Aztecs:

At the time Cortez sailed over to Mexico from Cuba, the Aztecs were the most powerful civilization in all of Mexico. The Aztecs had conquered almost every tribe, and so asked in return a crapload of tribute and human sacrifices (always better to use someone else's people than your own). Of course, being somewhat normal human beings, the suppressed tribes grew quickly to dislike the Aztecs. As people have pointed out already in this thread, the obsidion mases or blades of the Aztecs were perfect for Aztec vs. insert another Mexican tribe. The reason was the entire object of the "Flower Wars" was to capture as many of the enemy as possible to prove your strength in battle and to provide your emperor with as many human sacrifices as possible. This style of warfare did not prove successful against the Spanish, who would not hesitate to just flat out kill you. Also, the obsidion Aztec blades basically shattered and fragmented against the Spanish steel swords and armour, leaving the Aztec warriors unprotected. The sheer bravery the Aztecs possesed in battle, not to mention overwhelming numbers, was not enough to hold back the Spanish.

WHen the SPanish first arrived, the Aztecs were at a very big disadvantage. First, the Spanish possessedd a few cannons and many had arquebuses, or the Spanish muskets. The Aztecs were terrified of the loud "BOOM" these guns made, and did not know what to think of the huge smoke cloud they made. This, combined with the huge beasts the Spanish rode on convinced the Aztecs that Cortez might be a god, possibly Quetzalcoatl. Cavalry can easily demolish an infantry army, espescially an infantry army without pikes, one of the best counterattacks of the cavalry.

The early encounters between the Spanish and the Aztecs were a mix between gifts and skirmishes. On one such occassion, Aztec messangers sent from Montezuma himself presented many ornimants and gifts made of pure gold and silver. There were also approximately 30 slave women of mixed native background. One was (supposedly very beautiful) Malinche, or as Cortez came to call her, Dona Marina. She was born a Mayan but later sold into slavery to the Aztecs. After she very quickly learned a surprising amount of Spanish, she and Bernal Dias acted as Cortez's translators to the Aztecs.

Cortez, being the sly diplomatic soldier that he was, picked up some of Montezuma's enemies along his way to Tenochtitlan. The Tlaxcalans were the largest tribe numbering about 4000 soldiers dedicated to helping Cortez conquer the Aztecs. They also knew the Aztec's battle tactics and train of thought. At one place, there was like a small canyon type of thing with steep walls on both sides, and the Tlaxcalans told Cortez that the Aztecs would be waiting there prepared to ambush them. So, Cortez chose a different route. The Aztecs were so amazed, they once again went back to believing he might actually be Quetzalcoatl.

When Cortez reached Tenochtitlan, he acted like he wanted peaceful relations with Montezuma, and that he meant no harm. Soon, Cortez began ordering Montezuma to stop the daily sacrifices, and to convert to Christianity. Montezuma thought Cortez was crazy. Cortez ordered Montezuma to do other outrageous things, like bring him more gold (Some Aztecs actually thought the Spanish, being gods, ate only gold) and to punish his troops for starting fights with his Spanish soldiers.

Cortez, while in Tenochtitlan, received a message that Diego Velazquez had arrived in Mexico to arrest Cortez. Diego Velazquez was the governor of Cuba and was on poor terms with Cortez since Cortez left with a small band of soldiers, ships, and food to Mexico seeking personal glory. Cortez was supposed to be in jail in Cuba. So, Cortez again gathered some of his troops and allies from Tenochtitlan to meet Velazquez. The day of the battle, it was raining, and so of course the entire stock of gunpowder and cannons Velazquez had brought from Cuba was useless. Cortez and his allies smothered Velazquez, and I don't really know what Cortez did with him. I assume he killed him.

Cortez once again returned to Tenochtitlan and found the city in a riot. The small garrison of Spanish troops Cortez had left supposedly claimed the Aztecs were harrassing them so they went on a rampage and just massacred all of the Aztecs they could find. Cortez was more than annoyed at this.

Basically, Cortez once again returned to demanding things from Montezuma who by now was so pissed off with the Spanish presence that he actually started crying a lot whenever asked to convert to Christianity. The Aztec army was even more pissed off at both Montezuma and Cortez. Montezuma would not allow them to attack the Spanish, and the SPanish were eating the entire city's supply of decent food (ducks and birds from Lake Texcoco, bread, cornmeal, and other good foods).

Fighting finally broke out again, and Montezuma was hit by something, many people say an Aztec threw a rock at Montezuma and killed his own king on purpose. By now, the Aztecs had already appointed another king in place of the incompetant Montezuma, but he was soon killed among the fighting also. The Aztecs fled by canoe across Lake Texcoco, and Tenochtitlan was mostly burned to ashes or destroyed from the heavy siege and fighting.

Cuatemoc was the last of the Aztec kings, but was executed by Cortez for conspiring to kill him. Spanish intelligence told Cortez that Cuatemoc was planning a last Aztec insurrection.

It was not only that that the spanish had far more advanced technology, but they also had superior tactics and more general knowledge on warfare. Europe had beign fighting and developing new warfare techniques for millenia, before the Aztecs even existed. The spanish proffited from this tradition.

On the case of the aztcs, it's important to mention that they were so cruel to the tribes they ruled that many of those tribes were more then willing to fight alongside the spaniards. This provided the much needed numbers, as well as detailed information on terrain and the mechanics of the Aztec Empire.

On the case of Incands, it's important to mention that the Empire had just beign at Civil War, and the losers were brutally killed by Atualpa, the incan emperor. This not only made the Incans weaker, but also contributed to make the losing side willing to collaborate with Pizarro.

But technology was by far the single most important factor. Even if the Incans and Aztecs were powerful by american standards, they were still many many centuries behind Spain.

luiz said:

But technology was by far the single most important factor. Even if the Incans and Aztecs were powerful by american standards, they were still many many centuries behind Spain.

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I disagree. A few hundred men, no matter how advanced, cannot defeat an army of millions. Only with the help of native allies was it possible.

luiz said:

But technology was by far the single most important factor. Even if the Incans and Aztecs were powerful by american standards, they were still many many centuries behind Spain.

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Not so. Native Allies were by far the most important factor, for in reality the battles were more between the allies and the Aztecs/Incas, with the Spanish a minor elite force that could disrupt their lines. While the Spaniards made it possible for the allies to win the battles, the allies won the battles themselves, especially in the case of the Aztecs.

Teabeard said:

I disagree. A few hundred men, no matter how advanced, cannot defeat an army of millions. Only with the help of native allies was it possible.

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A few men with the controll of ICBMs could kill billions, to use a hyperbole.

As I mentioned in my original post the allies were of great help, but the superiority of the weapond and tactics of the spanish was the decisive factor.

There are many historical exemples of outnumbered armies winning due to superior weapons/tactics.

North King said:

Not so. Native Allies were by far the most important factor, for in reality the battles were more between the allies and the Aztecs/Incas, with the Spanish a minor elite force that could disrupt their lines. While the Spaniards made it possible for the allies to win the battles, the allies won the battles themselves, especially in the case of the Aztecs.

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The spaniardas did most of the fighting, I'm pretty sure.

As I said I don't deny the importance of the allies in both cases, but it was the superior technology that gave the edge that made the Conquista possible.

luiz said:

The spaniardas did most of the fighting, I'm pretty sure.

As I said I don't deny the importance of the allies in both cases, but it was the superior technology that gave the edge that made the Conquista possible.

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Not in Mexico. Their technology was used by the allies to outflank and punch through the lines of the Aztecs, which were the staple tactics of MesoAmerica.

Teabeard said:

I disagree. A few hundred men, no matter how advanced, cannot defeat an army of millions. Only with the help of native allies was it possible.

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Hard to say exactly how large the Aztec army was but there must have been thousands, hundreds of thousands. This is till the 16th century. Those muskets aren't exactly gatling guns that can mow down hundreds of men in seconds.

Hard to say exactly how large the Aztec army was but there must have been thousands, hundreds of thousands. This is till the 16th century. Those muskets aren't exactly gatling guns that can mow down hundreds of men in seconds.

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The mere fact that the Spanish possessed steel armour, steel swords, and horses was a dominating factor. With horses, they were able to some degree make up for their lack of knowledge of the land with scouts on horses, whereas the Aztecs had to travel by foot. The obsidian blades would barely dent the Toledo steel the Spanish wore, and in the time it takes for two or three Aztec warriors to swing their weapon, realize its uselessness against an armoured Spaniard mounted on a horse, the SPaniard could kill all three of them with his steel sword. I am not saying that every single Spaniard was wearing armour, and definately not full body armour, but those that were dominated the battlefield.

The muskets the Spanish used not only were VERY inaccurate, but their re-loading time made it almost useless when used in such a small army such as that Cortez brought to Mexico. The Spanish used them mainly for intimidation factors.

The Spanish definately could not have conquered the Aztecs with only the 500 men they had. Ever since they arrived in Mexico, the number slowly dwindled anyway from random skirmishes, disease, or sign of disloyalty to Cortez, which ultimately resulted in immediate death. I admire Cortez for setting the Galleons he arrived in ablaze, to settle any question in anyone's mind who was thinking about abandoning the army. The Tlaxcalans aided in scouting, sheer numbers in the field of battle, food, interpreters, and a ready supply of weapons. Anyone who says Cortez could have defeated the Aztecs w/out allies is out of their mind. They would have been so overnumbered that all 500 of them would have been tied to the stone and had their hearts cut out as human sacrifices.

How did the Spanish do it?

By having ruthless men, who had balls of steel, never mind guns and horses.

When considering the numbers they were up against, that it was a new land, the distances they had to travel, how isolated they were and that ultimately their main advantage was the swords they carried, it is incredible how the Aztec and Incan Empires fell.

The consolidation was the work of an empire, but these initial conquests were the work of small numbers of desperately greedy, ambitious men who put their lives on the line, gambled and in some cases won. Think of them as Tony Montanas. Of that initial wave that took down the Aztecs and inparticular those that did in the Incans, many came to a sticky ending.

kittenOFchaos said:

How did the Spanish do it?
By having ruthless men, who had balls of steel,
Think of them as Tony Montanas.

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.... but it's true, in addition to all the other factors, the conquistadores (probably some of the most unpleasant scoundrels to walk the earth) were not afraid to put themselves in dangerous situations

I think a major, major, major factor was morale. The spanish were after money and conquest. So they had major convidence. Where as the Aztecs and Inca were scared and intiminated. so they mostly ran, and gave up quickly.