The gladius has an interesting history with a lot of holes in it. Polybius says the Romans stole the design from the Spaniards. We have evidence of its use circa 380 B.C. and we know it was replaced by 200 A.D, but in between those dates the it has to be considered the most important weapon of the Roman Army.
Our story begins with the kings of Rome, most notably Severus Tullius, the fifth of the six, who reigned from 579-535 B.C. Roman folklore says that Severus built the first Roman army. Livy, who spun folklore into history, says the first three classes of soldiers in the Severan army carried swords. The fact that the other classes did not implies that they were not standard equipment until later. What this early sword looked like was unknown, although we have many sword types depicted on Etruscan pottery, so we might assume it was derived from those.
The adoption of the gladius in the Republican period is not well documented. We have the story from Livy of Titus Manlius who accepted the challenge to fight a Gaul. He fastened on his armor and picked up a shield and “Spanish” sword which was better adapted for close fighting than the Roman sword. As the combatants approached, the Gaul raised his shield to block any slashes from the Roman and swung his own sword at Manlius. Avoiding the blow, Titus leaned into the Gaul, stabbed him twice in the abdomen, and killed him. When did the Romans adopt this Spanish sword? We don’t know.
Using a thrusting sword in close quarters was described on a least two other occasions: against the Gauls in 387 B.C. as described by Plutarch and from Polybius describing Cannae and Telamon. In these cases, the author tells how the Gallic blades were inferior because of the quality of the metal and the lack of a point on the sword. The Romans had learned how to avoid the swings of the Gauls and stab them below the shield. The Gauls could only strike one or two blows before their swords bent and they would have to stomp on them to straighten them out.
A confusing story about the origin of the Gladius is given to us by Polybius. Quoting from a fragment of book twenty-two, “The Celtiberians excel the rest of the world in the construction of their swords; for their point is strong and serviceable, they can deliver a cut with both edges. Wherefore the Romans abandoned their traditional swords after the Hannibalian War and adopted those of the Iberians. They adopted, I say, the construction of the swords, but they can, by no means imitate the excellence of the steel or the other points in which they are elaborately finished.”
What was this ancestral sword they abandoned? Can we assume a pointed gladius did not exist before that time? Contradicting himself, Polybius told the story of an engagement by Flaminius in 223 B.C. where the Gallic swords are mentioned as having no points. This implies the Roman swords did have points.
Here is an example:
The purpose of the pommel is to balance the weapon.
The Roman gladii extant have lengths between 14.3 and 23.2 inches. The example shown above represents the Pompeii type which replaced the older Mainz type in the middle of the first century A.D. By contrast, Celtic swords were typically 21 to 33 inches long.
Legionnaires carried the gladius in a scabbard on their right side and they carried a dagger (pugio) in their left side. Some have argued that drawing the sword with the right hand would be too cumbersome while holding the shield in the left hand, but tests have proven that a right side gladius is quite accessible with the right hand. Centurions wore the gladius on the left because they did not carry a dagger.
The spatha eventually replaced the gladius around the year 200 A.D.
It’s interesting to look at the metallurgy of Gladii found in Europe. They are mostly wrought iron with carbon content at .03%. The edges were sharpened by forging (hammering) or sharpening on a wheel. Most were fabricated by placing strips of iron together in a sandwich. The quality is variable probably due to the skill of European smiths of the time.
The Romans, for the most part, used local smiths to fabricate swords for the army. Tacitus cites a case where Vespasian commanded that “strong cities be picked out so as to get their arms factories busy.” One of the more famous sword factories was located at Rheims.