A discussion about infantry combat in Aztec controlled Mexico, the medieval world, and in modern battle reconstructions.
The “Battle of the Nations” is an international sporting event held annually throughout Europe. Participants from France, Italy, the US, the UK, Spain, Russia, and many other countries engage in mock battles with dulled weapons. They come equipped with heavy steel armor and padding which severely reduces the damage and impact of their opponents weapons. As such, they are free to hit each other as hard as they want for the most part.
As far as I can tell, this is the closest thing that we have to truly authentic melee combat from the middle ages. Many mock battles attempt to effectively replicate the nature of battle in that period, but the participants often appear restrained and hesitant (as they should be). The mock combat scenarios found in the Battle of Nations seem very genuine, with a great deal of pushing, kicking, bashing, and even punching.
Although Aztec battle tactics and style may have looked very different, much of what we observe in modern recreations of melee combat is applicable cross-culturally.
The Aztecs drafted massive numbers of largely untrained commoners into their armies during campaigns. The Spanish historian Antonio de Solis y Ribadeneyra remarked how the Aztec armies swelled to massive sizes, with many uncontrollable soldiers who lashed out in rage, only to retreat out of fear. By contrast, anthropologist Ross Hassig uses the writings of Castillo and Sahagun (first and second hand sources respectively) to describe how ranks were kept orderly and soldiers had to obey their captains, else they might face execution or beating.
Hassig is knowingly describing these behaviors of soldiers with the understanding that battlefield conditions are far too chaotic and confusing for them to be enforced all of the time. These descriptions of formations and discipline are certainly ideal, but probably not always reflective of real world scenarios. Commoner soldiers who received some training in the Aztec telpochcalli might fair better than a simple peasant, but they still probably lacked the discipline necessary to remain calm and collected during a battle.
In Aztec period Mesoamerican warfare, when two opposing unit formations close for battle they release a salvo of atlatl darts and possibly even javelins. The elite units at the front of the charge then switch to a melee weapon, usually a macuahuitl, in order to better engage their foe. How exactly a soldier intends to attack his enemy is up to the current conditions and his personal preference. Attempting to strike the enemy soldier immediately would probably fail, as he would likely have anticipated this and raised his shield in response. As such, the tactic for this charge might be to simply raise your shield and crash into your opponent with the hope of knocking him to the ground.
The Aztec Cuachicqueh and Otomitl soldiers were extremely welled trained, elite shock units with years of military experience in campaigns across Mexico. Statistically speaking, these men would probably be stronger, more dangerous, and have more battlefield knowledge than the average soldier from that period. They would also (usually) outnumber whatever elite units were in the army the Aztecs were engaging. As such, the advantage would be theirs from the very first moments of contact.
Perhaps unit formations remained viable for some time, but I imagine that they would evaporate into a chaotic shouting and hitting match quite quickly. That being said, squad leaders, bannermen, and back-mounted standards (Pamitl), would help ensure that the two sides would remain mostly divided, with the Aztecs on one side and the opposition on another. If soldiers from different armies intermixed with each other across a battlefield, the resulting confusion could cause a bloodbath for both sides, or a rout.
In any case, the soldiers who fought for long enough and survived on the front line would be allowed to temporarily retreat for rest. Every 15 minutes or so, reinforcements would arrive and replace them, giving them time to replace or repair damaged equipment and hydrate.