is also one of the most significant technological innovation
s to warfighting
that our world has seen. Prior to the invention of the stirrup, while horses
were useful for transport
, they weren't useful for long rides or for fighting while mounted. Long rides were difficult due to the strain
of the rider maintaining all their body weight on their thigh
s, and fighting while mounted was not possible due to the need to hang on to the horse, as well as because there was no way to brace
. When your fighting is being done with edged weapon
s or lance
s of some variety, being unable to take impact is a Bad Thing.
One reason Temuchin's Mongols did so well is that they were one of the first large-scale, organized forces equipped with the stirrup. Riders could travel long distances quickly, and arrive in condition to dismount and fight. Alternatively, they could remain on their horses and defend themselves against footmen, all while wielding the massive kinetic energy and height advantage given them by the horse's strength and motion.
Armored horsemen would have been impossible without the stirrup, as the weight of an armored rider is nearly impossible to balance properly unless the feet are used and the stirrup spreads the load across the saddle. The stirrup also moves the interface between rider and horse lower down, closer to or even beneath the pair's center of gravity. This makes it much more difficult to topple the rider.
This is one example of a small thing having an enormous effect on warfare. There have only been a few others of this significance in history; there simply have not been that many fundamental changes in the conduct of warfare. Projectile weapons already existed long before the advent of gunpowder, both as handweapons in the form of crossbows and as artillery in the form of ballistas, trebuchets, catapults and other large leverage engines. As such, it is possible to argue with compelling force that gunpowder did not so much change warfare qualitatively as quantitively - projectiles reached farther, could be fired faster, did more area damage, etc. This is opposed to the change engendered by the stirrup, which made mounted warfare a possibility - the potential of harnessing a mount's strength, speed, endurance, and size to the control of the warrior.