In the midst of peoples physically stronger than they were, and very warlike in attitude, the Sumerians built a thriving Empire. They did this because they had both a better organized and better trained military. They also had better weapons. The Sumerians were the first to introduce bronze weapons, the infantry phalanx, and the chariot to warfare. They used the chariot and infantry phalanx in close support of each other with remarkable success.
For information on Sumerian weapons and equipment we rely on the inlay from the Royal cemetery of Ur, the weapons from the same graves and from those in the cemetery at Kish and the inlays at Kish for the fourth millennium BC. For the early third millennium BC we have the stela of the Vultures and the stela of Naram-Sin. For the later period we must rely upon the Law Code of Hammurabi, and notes from several royal and other inscriptions.
The Chariots used by the Sumerians were of heady construction and were pulled by four onagers (wild asses). Top speed as modern experiments have shown was about 15mph, but this was only obtainable on open and level terrain, also the chariots had a very wide turning radius at anything above their slowest speed. The chariots were used for crashing through the enemy infantry line. Experiments have proven that an ass (onager) would have been no more contrary than a horse when trained to pull a war cart. The modern view of the contrary jackass is just that, a modern view, and an old wives' tale, as anyone who has ever been on a hunt in the Rocky Mountains (in the United States of America) where they use jackasses for transportation can tell you. The mountain guides used jackasses for their surefootedness and their tractability, as they worry for the safety of the hunters they are guiding.
The chariots set low on four wheels each made of two pieces of wood fastened around their axles and tyred with leather. The car body was square with a step in the rear. The body was made up of a wooden frame covered by leather to protect the crew. The front was made up of two round topped shields with the reins passing through the V between the shields. The reins were often decorated with silver and lapis beads, these reins passed through a ring on the chariot pole and were attached to the silver headstalls, no bit seems to have been used. Each chariot had a crew of a driver and a warrior. The warrior used several short spears in combat and these were carried in a quiver attached to the front area of the chariot's fighting box. Some of these spears had the butts modified for use with a throwing thong, where the others had plain butts for hand to hand and close-in fighting.
The infantry fought in a close order phalanx that took training and organization. They wore conical copper helmets with fixed cheek-pieces, they wore what appears to be kilts made of leather strips sewn to a girdle fastened around the waist. They also wore long cloaks of what appeared to be animal skins or possibly heavy felt material with copper, stone, or wood discs sewn on for added protection. They carried short spears, and the front rank carried long shields. The Sumerians also had skirmishers and light infantry who wore lighter cloaks and carried light spears, axes, and curved bladed short swords.
Some people have claimed that Sumerians did not use Archers, but grave finds in Ur and Kish would seem to prove otherwise, that they did indeed use Archers in war. Copper and bronze arrowheads of a type that lend themselves more to warfare than hunting have been found along with the remains of bows with grips decorated with sliver, copper, and bronze.
Two types of spearhead have been found that are of special interest. One is a long thin pike like bronze or copper head of as much as two feet in length. The other is a broad leaf shaped head made of bronze that is 12 inches to 20 inches long and is sharp along both edges and could be used both for thrusting and slashing.
Many soldiers seem to have also carried adzes, axes, and daggers. There are inlays that clearly show Axemen and what appear to be men armed with maces with pear shaped heads.
In the latter period the chariot seems to have fallen out of use for combat, and the infantry are armed with longer and heavier spears. In this later period chariots seem to be much lighter and only used for transport by the nobles and other aristocrats. The infantry have discarded their cloaks and now carry much heavier shields. In the later periods the Sumerians also came to rely on more mercenaries from the Akkadians (a Semitic People), and Elamite hillmen.
The Sumerians were finally defeated and their Empire destroyed by the Semite Kingdoms. This defeat may have been caused by the fighting between the Sumerian city-states weakening the Sumerians so much they could no longer resist the invaders.