In the west, the usurpers of the Gallic Empire, such as Postumus (260–268),[15] Laelian (268), Marcus Aurelius Marius (268–269), Victorinus (269–271), Domitian II (271) and Tetricus I (271–274), managed to defend the borders of the provinces of Britain, Gaul and Hispania.

[16] Eutropius wrote: «As Gallienus abandoned the state, the Roman Empire was saved in the West by Postumus and in the East by Odenathus.» (translation from Latin)Postumus had in fact succeeded in establishing an empire in the West, located in Germania Inferior and Gallia Belgica and, shortly after, in all the other Gallic, British and Hispanic provinces including, for a short period, even Rhaetia.

[17] These emperors not only formed their own senate in the middle of the Treveri tribes and attributed the classical titles of consul, Pontifex maximus or tribune of the plebs to their magistrates in the name of Roma aeterna,[18] but also assumed the normal imperial title, minting coins at the mint of Lugdunum, aspiring to unify with Rome and, most importantly, never think of marching against the so-called "legitimate" emperors, who rules over the main empire, such as Gallienus, Claudius Gothicus, Quintillus or Aurelian.

They, on the contrary, felt they had to defend the Rhine borders and the Gallic coast from the attacks of the Germanic populations of Franks, Saxons and Alemanni.

[19] In the East, it was the Palmyrene Empire, also called the Kingdom of Palmyra, that rebelled and took over part of the provinces of Anatolia and Syria while invading Egypt, first with Odenathus (262–267), nicknamed by Gallienus as "Corrector Orienti ", and then by his secessionist widow, Zenobia (267–271).

[22] The Palmyrene prince succeeded, in fact, in inflicting notable losses on the enemy, so much so that the emperor Gallienus conferred upon him numerous honorary titles, including that of Palmyrenicus and dux Romanorum.

These victories earned Gallienus the honorary title of Persicus Maximus, and Odaenathus the one of Corrector Orientis, with jurisdiction over a large part of the Limes Orientalis.

The borders of Odaenathus' power, in those years, extended north from the Taurus Mountains and to the south until it reached the Persian gulf, including the provinces of Cilicia, Syria, Mesopotamia and Arabia Petraea.

[29] Shortly after his death, Zenobia took power, in the name of her minor son, Vaballathus, with the aim of maintaining autonomy from Rome, thus creating an independent state in the East.

The Vita Gallieni reports that the emperor sent against the Palmyrene Empire one of his generals, Aurelius Heraclianus, appointed dux of the expedition aimed at regaining control of the border with Persia after the death of Odenathus in 267.

[32] However, in light of these events, the belief that the Palmyrenes had the mission of governing the East was strengthened and Zenobia, guardian-regent of her son Vaballathus, only after the death of the emperor, Claudius, which occurred in 270, led the rebellion against the imperial authority.

Starting from 269, Zenobia implemented an expansionist policy, appointing the able general Septimius Zabdas as supreme commander of the Palmyrene troops, sending him to extend her power up to the borders of Bithynia[33] and Egypt.

[39] Aurelian, having solved the problems he had in Italy, decided to plug all the gaps in the Roman defensive system, restoring the integrity of the state on the old borders, starting with the Kingdom of Palmyra.

As a first move, he sent the future emperor Marcus Aurelius Probus, when he was still a general, to Egypt to reconquer for the imperial cause the territories lost a couple of years earlier to the advantage of the Palmyrene kingdom.

According to legend, Aurelian's clemency towards the inhabitants of Tyana was due to an apparition in a dream of the philosopher Apollonius who told him: «Aureliano, if you want to win, spare my fellow citizens.» (translation from Latin)Zenobia, meanwhile, prepared a mighty army under the command of Zabdas, the one who had conquered Egypt on behalf of the kingdom of Palmyra; the Palmyrene soldiers were mostly light archers and iron-armed horsemen.

Aurelian, realizing this, immediately took steps to repopulate the city by convincing the citizens who had fled to return with the promise that not a hair would be harmed, since they had been forced to obey the usurper out of necessity and not by will.

The Emperor meanwhile sent Probus to subjugate Egypt and headed towards Palmyra crossing the desert[59] and facing the Syrian-Arab raiders, who during a small clash, managed to wound him.

[63] But the Sassanid king Shapur I had just died of illness and only small aid was sent from Persia which was however easily intercepted and defeated by the Roman legions.

Zenobia then decided to mount the fastest of her dromedaries and attempt to escape but sixty miles from Palmyra she was reached and captured by the Emperor just before she crossed the Euphrates.