The pilum is an italic weapon that corresponds to a specific type of fight. Its main characteristic is its long iron shank and its relatively small head as compared to other types of spears of its time.
It is mainly a missile weapon designed to break the enemy line. This is why it is designed for maximum penetration on impact. Once it had penetrated, the iron shank, softer than the head will bend preventing the enemy to throw it back. If the pilum penetrate a shield, the warrior has no time to tear it out and is thus forced to abandon his shield. In close combat, this very often means death!
There are 2 main categories of pilum, the light, and the heavy. There are however many variants within these categories that can adapt to various types of opponents and combat situations. According to Polybius writings in the second century BC the legionary carried 2 pilums the heavy and the light. In combat the lightweight pilum is discharged first as it bears a longer range, then the heavy pilum with a better penetrating power and then the gladius is drawn as illustrated by Peter Connolly below.
The corpus of the Republican pilums found in 3 places and 3 different periods shows us a great similarity of most models:
those found at Šmihel in Slovenia are dated from the end of the 3rd century B.C.;
those found at Numantia in Spain date back to the middle of the 2nd century B.C.;
those found at Alesia France date back to the middle of the 1st century BC.
They display quite a variety in size and head forms. It can thus be deduced that each pilum style must have had a different technical use and was adapted to a specific type of opponent. One can for example rightly think than a fine, square head better penetrate an opponent with a metallic armor, and that a wide triangular spike will be most appropriate against the cavalry or a foe who does wear heavy protections.
One can also think that very short models were originally long ones that have been hastily repaired for another use after having been broken in a previous battle.
The illustrations above show heavy pilums found in Slovenia and Spain & our reconstructions are made by Kurt der Schmid of AERA Austria.
Bottom illustrations show light pilums and our proposed reconstruction of one of these models.