Battle of Carrhae, where the Romans were well and truly gubbed by the Parthian Empire. Classic story of an overconfident and poorly-led force going up against an enemy they didn’t understand.
Helps that the Romans were led by Marcus Licinius Crassus, who you might remember being played by Olivier in ‘Sparticus’.
Loads of very cinema-friendly images in the historical accounts: Roman legionaries attempting to charge and finding that they were literally pinned to the ground by arrows, or Crassus losing his marbles after a Parthian cavelryman charged along his lines with his son’s head on a pike.
According to some (probably less reliable) accounts, Crassus, having been captured after the battle, was executed by having molten gold poured down his throat; a reference to his having been worth a bob or two.
Hope they keep Ridley Scott away from it.