Odenathus, Zenobia's husband, was commander of the Roman forces in the east (according to Zosimus he 'joined to the remainder of an army that still remained in the country many of his own troops'), and it's possible that after his death some of them might have remained in Zenobia's Palmyrene army.
The
Historia Augusta, however, states that the Temple of the Sun at Palmyra was 'pillaged by the eagle-bearers of the Third Legion, along with the standard-bearers, the dragon-bearer, the buglers and trumpeters...' (H.A
Aurelianus, 31.7) This was following the final sack of the city. The Third Legion are almost certainly III Gallica, which had been stationed in Syria for about two centuries by this point, and would have been one of legions under the command of Odenathus. By this point, however, they were clearly fighting for Aurelian! So it seems like at least part, and maybe all, of the Roman garrison in the east remained loyal to Rome after Zenobia's accession.
Zosimus (
Historia Nova) describes the army that Zabdas leads against Egypt as comprising 'Palmyrenians, Syrians, and Barbarians, to the number of seventy thousand', and later Zenobia's force consists of 'Palmyrenes and their allies'. So we can imagine a pretty mixed bunch. The
Historia Augusta describes 'squadrons of Saracens and Armenians' (probably light cavalry) being bribed by Aurelian to change sides - these might have been some of the 'barbarians' Zosimus mentioned.
The battle descriptions in Zosimus provide a bit more information on the 'vigorous cavalry of the Palmyrenians': they 'placed great confidence in their armour, which was very strong and secure', and 'they were much better horsemen' than the Romans. Because of this, Aurelian orders his own cavalry to make a feigned retreat, drawing Zenobia's horsemen into a long pursuit 'until they had wearied both the men and their horses through excess of heat and the weight of their armour'. Later, in the battle of Emesa, Palestinian clubman are sent against the disordered Palmyrene cavalry, using 'clubs and staves against coats of mail made of iron and brass'. (H.A. Book I. 25-27). The impression given is that the Palmyrene cavalry were more heavily armoured then the Romans, and attacked at a charge ('vigorously') and in formation - this would suggest cataphracts or clibanarii.
All the quotes above are from these online sources:
Zosimus, Historia Nova
Historia Augusta, Divus Aurelianus
- Nathan