Egyptians were masters of chariots. In the battle of Kadesh, 5-6 thousand chariots were used against the Hittite. The chariots, like cavalry archers by later armies, would charge but stop close to enemy. From there they would be able to take good aim at the infantry body parts not protected by armor. Javelins are hurled against pursuing cavalry or heavy infantry with shields and armor.
As depicted in movies Ben Hur and gladiator, the chariot can actually travel faster than a horse plus rider galloping. The speed, the momentum and the cloud of dust that a chariot charge creates is actually terrifying and primitive armies had no solution to it.
Like cavalry, chariots are great to concentrate firepower towards enemy weakness and bolster allies who are getting overwhelmed. Their ability to flank, charge from rear can easily create panic esp. against untrained soldiers. Imagine the plight of a pedestrian seeing a one ton car charging towards it. The ability to pursue retreating soldiers is advantageous to achieve regicide (kill/capture of the king/general) and ensuring the enemy does not escape with food and valuables.
Chariots were great against elephants as well because of their unique ability to maintain safe distance and fire while retreating. Here the goal is to attack from the side where there was no armor rather than front, distract the animal and prevent it from charging forward. Charioteers would taunt and poke the beast it goes berserk and steer it away from the battlefield. Ancient armies had not solution to neutralize elephants and that was the reason why Hannibal campaigned undefeated for years in Rome and even Akbar maintain a fleet of 1000 war elephants at huge cost to the exchequer.
Walls and large earthwork were rare in ancient times and most civilizations were close to flat riverbed plains making the battlefield ideal for such maneuvers. Most chariots operated in large fleets over plain fields without tree cover making it difficult to trap or surprise the chariot from which they could not escape. If few chariots get trapped or their wheels get stuck, their friends would lend a hand and rescue them. Hence making them unstoppable in ideal terrain.
Early chariots looked like lightweight I shaped structures designed for speed, suspension and stability. This I shape has not changed even for modern cars, axle in one end and powertrain in the other with a beam to connect the two. This created the connecting beam as a very stable torsion spring preventing the chariot to overturn during maneuvers. The rear axle was not nailed to the beam but allowed to make making it the first suspension designed by man. The walls & floor of the chariot carriage were from woven leather hides or wicker making it light weight yet strong for an era without plywood or metal sheets. The beasts were tied using a horse collar/saddle pads with a breast collar and not the ox yoke because of the difference of horse anatomy from the draft beasts.
Ancient engineers understood wood as a composite material and leveraged on steam-bending, bonding, layering to maximize the strength & lower the weight. Certain structural parts were covered by metal sleeves for reinforcement. However wheel getting dislodged and capsizing of the vehicle during the charge was common problem of the era.
The wheels is where the craftsmanship differs from nation to nation. Nobody had ball bearings or effective lubricant or springs and yet they were able to achieve speeds of 20 km/hr. The first wheels were solid wood but gradually engineers started reducing weight and improving the joints. They went for hub and spoke model with 4 spokes (too bumpy as it was difficult to maintain curvature) to 8 spokes that weighed almost as much as the solid wheel. Boring a hole in the hub to attach spoke made it weak and prone to failure. Egyptians solved this problem by creating V shaped wedges glued together to create the hexagonal star wheel. The spokes would act as spring leaf as the wedges would like to straighten itself and thus redistributing pressure on the hub. Chariots wheels that were not in use tended to deform under its own weight. They went for 6 spokes which they found to be the ideal tradeoff between weight & durability.
Also they experimented with various axle position. The front of the carriage would save on weight on the connecting beam, the middle on the cost as it helps do away with the flooring and the rear (preferred by Egyptians) minimized the vibrations making aiming while retreating more accurate.
The sight of Persian Scythed chariots with their long blades gives and impression that chariots were used as shock force. A shock force is the charge of medieval knights designed to break the enemy infantry formation, cause a rout and cut off the retreat. The knight’s lance has to face the enemy to be effective and not away from it, then why are the chariot’s blades are pointed sideways? They were the first kind of bayonet designed to protect, give mental insurance to the defenders rather than to provide tactical advantage. Wheels are chariots Achilles heel and the enemy had to just poke a spear to immobilize the chariot. Scythes is a deterrent for the enemy for such mischief. In addition, it provides some protection to prevent chariot from toppling during turning or uneven surface.
Especially designed heavy chariots were sometimes used to break the heavy infantry formation, but such charges were rare due to the cost involved and the fact that the team would be spent and cannot participate in the battle further. Hence in such occasions these charges of heavy chariots would be accompanied by infantry marching few feet behind to immediately capitalize on the opening or the beachhead provided by the chaos that it ensures in the enemy ranks. Alexander was able to counter this tactic through disciplined trained heavy infantry with 20 feet long poles, but before him no infantry stood a chance. However these were less of chariots and more of war wagons with a payload of barbs, incendiary oil and the charioteer would be in the rear rather than the middle to facilitate safe extraction. The horses’ eyes were sometimes covered, but the sheer bulky momentum of the carriage would prevent the horses from stopping at the sight of the
By 300BC the chariots technology was perfected and there were very little enhancements that Romans could do in the centuries of chariot racing that followed. However till the advent of internal combustion engine, nobody could solve the limitation of conducive terrain and weather needed by chariots to operate.