Charioteers Special Attack?

Playing the Julii 1.3 and noticed the Brits were making some chariot units; some light, some heavy. For the first time ever, I noticed in the unit description of heavy chariots (I think) something which said: "Special attack" or "Secondary attack".

Now, it took me forever in RTW to discover that you could get cataphracts to use a secondary attack with their maces. My question is, what's this "special" or "secondary" attack of the British chariots? The heavy ones don't have any missile attack. The only thing I can think of is the way they plow through infantry and flip them into the air. But is that all? If you Alt+attack do they actually start to kill people? (I remember being appalled by the non-lethality of the heavy chariots the first time I played the Britons. Couldn't even kill a unit of routing peasants.)

CountMRVHS

It most likely is referring to the scythed attack. There is a projection off of the axle of the chariot on either side that represents a scythe blade. The chariots do this "naturally" as best I can recall. Similarly, elephants have a deadly radius associated with the front of them.