Pilum

The pilum (: pila) was a javelin commonly used by the Roman army in ancient times. It was generally about 2 m long overall, consisting of an iron shank about 7 mm in diameter and 600 mm long with a pyramidal head, attached to a wooden shaft by either a socket or a flat tang.

History
The pilum may have originated from an Italic tribe known as the Samnites. It also may have been influenced by Celtiberian and Etruscan weapons. The pilum may have derived from a Celtiberian weapon known as the falarica. Archaeological excavations have disclosed pila in tombs at the Etruscan city of Tarquinia. The oldest finds of pila are from the Etruscan settlements of Vulci and Talamone. The first identified written reference to the pilum comes from The Histories of Polybius. According to Polybius, more heavily armed soldiers of the Roman military used a type of spear called the hyssoí. This may have been the pilum. The precursor to the pilum was the hasta. It is unclear how soon it was replaced by the pilum. Polybius mentioned that it was an important contributor to the Roman victory at the Battle of Telamon in 225 BCE. Use of the pilum was discontinued by Roman military in the second century.

Design
A pilum had a total weight between 2 and 5 lb, with the versions produced during the earlier Republic being slightly heavier than those produced in the later Empire.

The weapon had a hard pyramidal tip, but the shank was sometimes made of softer iron. The softness could cause the shank to bend after impact, thus rendering the weapon useless to the enemy. Some believe that the pilum was not meant to bend on impact, but instead was meant to break. If a pilum struck a shield, it might embed itself, and the bending of the shank would force the enemy to discard his shield as unusable without removing the pilum, or carry around the shield burdened by the weight of the pilum. Even if the shank did not bend, the pyramidal tip still made it difficult to pull out. Many cases occurred, though, in which the whole shank was hardened, making the pilum more suitable as a close-quarters melee weapon and also making it usable by enemy soldiers.

Although the bending of its shank is commonly seen as an integral part of the weapon's design and as an intentional feature, little evidence suggests that. The most commonly found artifacts suggest that the pilum was constructed to use the weight of the weapon to cause damage, most likely to be able to impale through armour and reach the enemy soldier's body. The combination of the weapon's weight and the aforementioned pyramidal tip (the design of which was seen in the Middle Ages in the form of bodkin arrow tips), made the pilum a formidable armour-piercing weapon. If the weapon was meant to be used against armour and to use its mass (as opposed to its speed) to cause damage, the bending of the shank seems to be a beneficial result of its intended use, which is to pierce through layers of armour. That the pilum needed to pierce layers of armour (through the shield, into body armour and past clothing) necessitated a lengthy shank, which was prone to bending. M.C. Bishop wrote that the momentum of the pilum caused the shank to bend upon impact, and although unintended, that proved a useful characteristic of the weapon. However, a newer work by M. C. Bishop states that pila are "unlikely to bend under their own weight when thrown and striking a target or ground"; rather, human intervention such as improper removal of a pilum stuck in a target is responsible in some way, and Caesar's writings should be interpreted as the pilum bending when soldiers tried to remove them. Since the pyramidal tip of a pilum was wider than the rest of the shank, once it had penetrated a shield, it left behind a hole larger than the rest of the shank, and it could move through the shield with little resistance, stabbing the soldier behind. The length of the shank and its depth of penetration also made pulling it out of a shield more difficult, even if it failed to bend. If the bearer of the shield was charging and a pilum penetrated the shield, the end of the heavy shaft of the pilum would hit the ground, holding the shield in place. Some pila had a spike on the end of the shaft, which made it easier to dig into the ground.

The two versions of pila are heavy and light. Pictorial evidence suggests that some versions of the weapon were weighted by a lead ball to increase penetrative power, but archaeological specimens of that design variant are not (so far) known. Recent experiments have shown pila to have a range around 33 m, although the effective range is up to 15 - 20 m. The earliest known examples of heavy pila have barbed heads and their tangs have a figure-eight shape.

Romans also used the pilum as a melee weapon in close-quarters combat. Note pictorial depictions from the Tropaeum Traiani monument, descriptions of Caesar's troops using javelins as pikes against the Gauls in Caesar's Gallic War, Book VII, and descriptions of Caesar's men using javelins to stab at Pompey's cavalry in Plutarch's Life of Caesar.

The angon was a similar weapon used in late Roman and post-Roman times.

The origin of the design of the pilum is a matter of contention. Arguments have been proposed which suggest that the design stemmed from ancient Italian tribes or from the Iberian Peninsula. Considering that two versions of the pilum are known (the heavy and the light), the Roman pilum may be descended two different weapons, perhaps from different cultural groups. The two weapons designs may have coalesced into the form of the typical Roman pilum as it is known today.

Tactics
Legionaries of the late Republic and early Empire often carried two pila, with one sometimes being lighter than the other. Standard tactics called for Roman soldiers to throw one of them (both if time permitted) at the enemy, just before charging to engage with the gladius; however, Alexander Zhmodikov has argued that the Roman infantry could use pila at any stage in the fighting. Zhmodikov has also argued that Roman battle tactics sometimes consisted of exchanging projectile weapons such as the pilum. Sam Koon argues against the idea that Roman tactics primarily consisted of projectile combat.

The effect of the pilum throw was to disrupt the enemy formation by attrition and by causing gaps to appear in any protective shield wall. The design of the pilum's tip is such that once wedged inside a shield, it is difficult to remove; a shield thus penetrated by a pilum became very awkward to wield, and was usually discarded. This resulted in the aforementioned gaps in the protective shield wall, which could then favour the short gladius in tight hand-to-hand mêlées.

Pila could also be used in hand-to-hand combat; one documented instance of this occurred at the Siege of Alesia, and another during Mark Antony's Parthian campaign. Additionally, pila could be employed as a thrusting implement and a barrier against cavalry charges. Some pila had small hand-guards, to protect the wielder if he intended to use it as a mêlée weapon, but apparently this was common.

Vegetius' commentary
The Roman writer Vegetius, in his work De re militari, wrote:

"As to the missile weapons of the infantry, they were javelins headed with a triangular sharp iron, eleven inches [279 mm] or a foot long, and were called piles. When once fixed in the shield it was impossible to draw them out, and when thrown with force and skill, they penetrated the cuirass without difficulty."

And later in the same work:

"They had likewise two other javelins, the largest of which was composed of a staff five feet and a half long and a triangular head of iron nine inches [230 mm] long. This was formerly called the pilum, but now it is known by the name of spiculum. The soldiers were particularly exercised in the use of this weapon, because when thrown with force and skill it often penetrated the shields of the foot and the cuirasses of the horse."

Arguably, a short iron shaft has very few confirmations from archaeology. Vegetius wrote about a one-foot iron shaft because at his time, the pilum had disappeared and been replaced by similar shorter weapons such as the plumbata and spiculum.

Results of experimental archaeology
Due in part to experimental archaeology, the design of the pilum is believed to have evolved to be armour-piercing; the pyramidal head would punch a small hole through an enemy shield, allowing the thin shank to pass through and penetrate far enough to wound the man behind it. The thick wooden shaft provided the weight behind the punch.

In one description, one of the two iron nails that held the iron shaft in place was replaced with a weak wooden pin that would break on impact, causing the shaft to twist sideways. Gaius Marius is sometimes given credit for that modification. Archaeological evidence from the 80s BC through to the early imperial era show that this redesign was not adopted.