Quote Originally Posted by O'ETAIPOS
I can easily believe that roman loses were much bigger, but what reason is there to claim that losses of Antiochos were small?

Antiochos's army had only 19000 foot troops worth mentioning (phalangitai and galatians) and possibly up to 10000 silvershields (Bar-Kohwa's opinion)
The rest was composed of light armed levees, mostly useless as it was raining (the worst weather for composite bows).
Hopefully my explanation will be convincing. I'm pretty sure though that Livy mentions the Argyraspidai on the extreme right.

Romans on the other hand had around 20000 heavy infantry, quite probably veterans of II Punic and II Macedonian wars.
Recently the concession seems to be that they had more. Possibly upwards of 50,000 total minus sick and wounded. It comes from careful reading of Livy and his mentions of troops that have been stationed throughout Italy and Greece - troops which would have been brought over to Asia Minor to fight Antiochos. I have it posted in EBH if you're curious.

If we add to this that Antiochos left wing was broken minutes after the battle started (own chariots and Roman/Pergamene cavalry charge) we see that the situation was not very good for Antiochos.

Phalanx and galatians were surounded by romans, inf and cav, and was massacred so we can assume 70% dead here. Another massacre was done in the camp, so I think we can easily assume 25000 dead plus 5000 trampled by elephants and people in retreat. Some were also taken prisoner.
Right, but not of the cavalry is going to wait around and be killed. Considering how much cavalry was on the Seleukid left I wouldn't be surprised if more than half got away. Seleukos IV was in command of that cavarly - how did he get away then?

The phalanx that had formed the square was holding back the Romans quite well. That is, until the elephants rampaged. 5,000 is a bit high though - I would have put it at less than that. Plus, once the elephants did rampage, it probably scared off the Roman soldiers and allowed the phalanx troops to break and flee.

I imagine that the 4,700 light infantry stationed to the left of the phalanx probably broke and ran after having seen the cataphracts collapse due to the chariots. Same with the other cavalry in that area like the "Tarentines". The heavy fighting described by Livy at the camp afterwards was probably due to the light troops put there to guard the camp. I don't even think there is enough frontage to put the several thousands that Livy describes anywhere on the battlefield other than at the camp - which would explain why the phalanx, so easy to break at Thermopylai when troops appeared at their rear, held almost indefinitely at Magnesia. That is the one place were casualties would be incredibly high, but I have a feeling that if Livy's number of 35,000 is anywhere accurate that might be because it includes dependents and slaves which were at the camp (a bad Hellenic practice).

Finally, after the battle Seleukos is at the Antiocheia of the region, which is due west of Magnesia, with a sizable army. Where did this army come from if not from Magnesian survivors? It was apparently large enough of an army that Rome avoided it entirely. If you have a drastically reduced phalanx and troops of other contingents then you have nothing suitable to defend the city.