Proper usage of Oxybeles in field battles?

[The Ferret]

I just got the opportunity to use the Oxybeles ("ballista"-type siege engine) for the first time in a large field battle, my (Ptolemaioi) full stack vs. Makedon full stack and then some.

I placed the Oxybeles front and center in a gap in the middle of my phalanx, on a slight rise so hopefully they would have a firing line over my skirmishers. Since I figured they would be an obvious target for enemy cavalry (as indeed they were), I put the army's unit of Hypaspistai immediately behind them as their designated protection.

I was... slightly underwhelmed by their power. At first I had them on hold fire so I could designate obvious targets for them - hoplites in close order instead of skirmishers in loose formation, for example. Then, after I figured ammunition wasn't a problem, I put them on free fire.

The battle statistics screen showed a grand total of 8 kills for them, versus >100 for my slinger and archer units.

The initial enemy wave did rout very easily - does the Oxybeles' firing frighten enemies? But they took the brunt of a charge by the enemy general and had to abandon their weapons, and that wave routed even easier, so I think the enemy armies just had low morale for some reason.

How have others used this weapon in field battles? What would be a better way to employ it?

[QuintusSertorius]

I didn't think they were a field battle weapon at all, but rather a siege weapon for battering down walls.

[The Ferret]

I didn't think they were a field battle weapon at all, but rather a siege weapon for battering down walls.

The description says it's an anti-personnel weapon (particularly good for shooting troops on battlements), and it doesn't look like enough to even damage a stout wooden gate - it fires a bolt about the length of your forearm.

[rovert]

They are useless atm , don't know if that will change & he is talking about the Scorpions .
I have tested them through and through , any group of range troops are better , they fire way to slow to be of any use.

[Rafkos]

I have tested them through and through , any group of range troops are better , they fire way to slow to be of any use.

Perhaps giving them more scorpions per unit and increasing slightly their reload speed would make them more useful?

[Sar1n]

Oxybeles are quite...difficult to use. It IS possible to use them effectively, especially with phalanx, but you need to have terrain on your side. Slight elevation behind your phalanx is best for it, place it a little bit more behind your line than archers, to account for their flat trajectory.

Basically, their purpose is to keep enemy under ranged attack, weakening their morale and causing casualties slowly. While most ranged units will fire their load quite early in battle, Oxybeles will keep it pouring on enemy throughout whole battle. They're best used to fire across the line on the heavy units that are putting pressure on your defending flank (usually...at least usually for me, the battle turns hot around flanks of my phalanx, and I keep one flank holding while the other goes on offensive to roll up the enemy). Don't fire on units close to the Oxybeles, you'll cause a lot of friendly fire on units between it and enemy. They're also quite effective at destroying enemy elephants.

[The Ferret]

I tried as you suggested, Sar1n - had a battle in hilly country, so put them above my phalanx. Using flaming ammunition this time, they were quite effective, especially shooting at enemy troops in reserve. 118 kills in a long battle, comparable to other ranged units. Thanks for the advice!