I'll elaborate a little (I did a lot of projects on ancient Rome): The pila were javelins. Legionnaires typically would carry two into battle, crossed behind their shields. Sometimes they would be two identical javelins, sometimes they'd carry one "light" one and a heavier one. Now, the purpose of the pila javelins is obvious- to kill the enemy, right? The entire formation gets within throwing distance, order is given, and the disciplined men all throw nearly simultaneously into the enemy formation. Some of these will end up impaling the poor bastards on the other side, yes... but the real danger of the pilum- **IT WAS A SHIELD WRECKER.** The shaft of these pila would often be weighted on the blunt end. See the long metal head of the javelin? That shit will bend downward once it's thrown into a shield. Now imagine you're holding a shield, and 3 of these fucking things pierce it. You're fortunate enough that none of them managed to stab you, but suddenly your shield feels about 40x heavier and it's just being sucked downward to the ground.... all the while, a formation of vicious Roman warriors is now *sprinting at your in formation.* Your only reasonable option is to ditch your shield. And losing your shield in this kind of situation is like a death sentence. The Romans were very clever when it came to battlefield tactics and overall strategy. The pila serving more purposes than just "poke hole in bad guy" is just one of many examples. Hell, the Romans may have made the first repeating ranged weapon, a sort of automatic crossbow artillery piece... in like 300 BC.