High Imperial Roman army vs Late Roman army

[Marja]

I think there seem to be an awful lot of thrusting spears on the Column of Marcus Aurelius. Maybe these are intended as pila, but they look more like shortened thrusting spears, and they are occasionally used in close combat. So I think the switchover occurred sometime in the second century.

I understand that Republican gladii tend to be longer than Imperial gladii, so it's hard to generalize about the roles of all gladii and all spathae.