According to Synesius of Cyrene (who however confuses Carus with Carinus), the shah of Persia Bahram II, having learned of the Emperor's warlike intentions, he tried to convince him to sign a peace.

They found Carus while he was having dinner: he took off his cap, which hid his baldness, and swore to the ambassadors that if the Persians did not recognize the supremacy of Rome, he would have made Persia as treeless as his head was hairless.

[16] Regardless of the groundlessness of Caro's alleged return to Rome, Some modern authors argue that it cannot be excluded that during the continuation of the Sassanid campaign Carus died in battle against the Huns (perhaps mercenaries in the pay of the Persians), according to them, a more plausible version than that of death by electrocution.

[20] The latter may have been artfully created by Roman propaganda to hide the defeats of Carus and Numerian in the final phase of the campaign handed down by some late Byzantine and Armenian chroniclers (whose reliability has however been questioned).

Many modern scholars prefer to discard or ignore the version of Carus' death against the Huns, arguing that the emperor died of illness or because of alleged intrigues of the praetorian prefect Arrius Aper.

However, the excessive slowness of the ride during the retreat (1,200 miles traveled in 16 months) It appears suspicious, and could indicate a possible continuation of the war against the Persians, which is also suggested by the poet Nemesianus' Cynegetica (which hints at the intention of writing in the future also about Numerian's Persian deeds, something which however never happened) and from the numismatic evidence (which, for propaganda purposes, would seem to suggest that Numerian had successes over Persia, which however, if there were any, must have been only partial, judging from the fact that the coins never attribute to him the cognomina ex virtute of Parthicus and Persicus).

[31][12] Even with all these problems of accuracy, it is plausible that at least the figure of Numerian's defeat is correct, making the spontaneous renunciation of conquered lands useless and explaining some inconsistencies in the "vulgate" version.

According to Porena's reconstruction, Numerian initially had to face a counterattack by mercenaries in the pay of the Persians against whom Carus died, then, after a truce of several months during which he would have wintered in Syria, apparently at Emesa (where he promulgated two rescripts dated September 283 and March 284), in the course of 284 he would suffer a serious defeat on the Euphrates, followed by the definitive Roman withdrawal.

[32] According to Zonaras,[2] Eugropius[3] and Festus,[4] the campaign ended in a Roman victory, with the conquest of Seleucia and the Sassanid capital of Ctesiphon (near modern Al-Mada'in, Iraq), cities on opposite banks of the Tigris[34][35][36][37] In celebration, Numerian, Carus, and Carinus all took the title Persici maximi.

According to the traditional reconstruction, the way back, 1,200 miles along the Euphrates River, was traveled in an orderly and slow manner: in March 284 they were at Emesa, in Syria, in November again in Asia Minor.

[40][41] During his campaign, Carus proceeded through Thrace and Asia Minor, annexed Mesopotamia, pressed on to Seleucia and Ctesiphon, encountering little resistance due to the Sasanian Empire's internal instability,[42][43] and marched his soldiers beyond the Tigris.