Inca battle tactics on open ground had proved to be highly effective against other competing civilizations in the pre-Columbian period. The arrival of the Spanish Conquistadors, however, was to expose the Inca civilization to a new form of warfare, both tactically and technologically.
Standard Inca Tactics before the Spanish Conquest
Standard pre-Columbian Inca battle tactics in open terrain relied heavily upon an initial ranged attack followed by a mass infantry charge at the enemy. Generally, one third of the main body of the army would launch a head-on attack while reserves would try to outflank the opposition. Disciplined and determined, Inca warriors were more than capable of obeying commands and executing tactical maneuvers without breaking formation or fleeing from the field.
Inca Battle Tactics versus the Spanish Conquistadors
The arrival of the Spanish Conquistadors, however, posed a new tactical problem to the might Inca civilization. While the importance of Spanish Conquistador weaponry and mounted units is often overstated (they did, after all, begin their campaign against the Inca with only a little more than 100 infantry and 62 horses), standard Inca battle formations proved highly susceptible to cavalry charges.
Inca warriors would often find themselves fighting Spanish armies which consisted largely of familiar tribal enemies; native rivals now sided with the new invaders. However, the Spanish units could deliver shock attacks the likes of which the Inca had never seen. Tactically, both Conquistador infantry and cavalry units could be used to strike decisively when and where needed.
Cavalry units, in particular, gave the Spanish greater mobility on the battlefield. Mounted units could be used to both rapidly counter standard Inca flanking maneuvers and launch vicious attacks of their own against the Inca flanks and rear. Even after the initial psychological effect of these Conquistador horses had lost much of its impact, it was still all too clear that the Inca would have to adapt to this new threat.
Inca Tactical Developments – Defensive Measures
As military historian Ian Heath states, “the arrival of the Spaniards resulted in tactical changes, but these were largely of a defensive nature prompted by the effectiveness of Spanish cavalry”. It soon became clear to the Inca that defensive measures were needed in order to counter Spanish cavalry, especially in open terrain. Two tactical ploys were favored by the Inca: fight in terrain that would naturally restrict the effectiveness of horses, or alter the terrain in order to impede them.
The Inca began to favor, where possible, battles and skirmishes in restrictive terrain: mountain passes, wetlands and jungle, for example, which would naturally limit the effectiveness of mounted troops. Tactical usage of narrow defiles also proved a successful strategy; the Spaniards would be allowed to enter (or led into) a narrow pass before being attacked from above with boulders, slings and arrows.
Where battle in open terrain was unavoidable, the Inca began to dig large holes filled with sharpened stakes. Cavalry would be lured towards these pits, which were covered with earth and vegetation, and if the horse fell for the trap then both animal and rider would often be killed. Where time or terrain did not allow for such large constructions, smaller holes would be dug with the intention of tripping the horse and bringing down the rider.
The Tactical Failings of Inca Warfare against the Spanish Conquistadors
Despite recognizing the need for new counter-measures against the Spaniards, Inca tactics did not adapt quickly enough to fend off this new threat. Historian Terence N. D’Altroy highlights some key elements inherent within Inca warfare, elements that often served to hinder them against the Spanish: “the concentration of massed force, the physical leadership of the army by its officers, the three-pronged attack, and the collapse of the army’s discipline with the loss of its command”.
The Spanish, once aware of the ancient Inca battle strategies, would look to take down the commanding officer in the front ranks of the enemy army, knowing that the Inca warriors would often break and run without leadership. The Inca’s overreliance on numbers could come crashing down around them once the chain of command had been broken.
Inca Weapons Largely Ineffective against Spanish Cavalry
Importantly, Inca warriors never managed to use what weapons they had (and never developed new weaponry) to successfully defend against cavalry. Despite having skilled spear units within their ranks (with spears as long as 20ft by some accounts), the Inca did not learn to use these weapons effectively against the Conquistador cavalry.
While the Araucanian Indians (Mapuche) in Chile used spear walls to great effect against Spanish cavalry, the Inca military did not adapt quickly enough to hold off the Conquistador forces. While many factors worked against the Inca in their struggle against the Conquistadors, the lack of adaptability shown by the Inca military certainly did not help their cause.