On the whole, however, the reign of Alexander was prosperous till he was summoned to the East to face the new power of the Sassanians. Of the war that followed we have very various accounts; Mommsen leans to that which is least favourable to the Romans. According to Alexander's own despatch to the senate he gained great victories. At all events, though the Persians were checked for the time, the conduct of the Roman army showed an extraordinary lack of discipline. The emperor returned to Rome and celebrated a triumph (233), but next year he was called to face German invaders in Gaul, where he was slain (on either March 18 or 19 235), together with his mother, in a mutiny which was probably led by Maximinus Thrax, a Thracian legionary, and at any rate secured him the throne.
Alexander was the last of the Syrian emperors. During his reign, acting, as he did in most things, under the influence of his mother, he did much to improve the morals and condition of the people. His advisers were men like the famous jurist Ulpian, the historian Dio Cassius and a select board of sixteen senators; a municipal council of fourteen assisted the urban preafect in administering the affairs of the fourteen districts of Rome. The luxury and extravagance that had formerly been so prevalent at the court were put down; the standard of the coinage was raised; taxes were lightened; literature, art and science were encouraged; the lot of the soldiers was improved; and, for the convenience of the people, loan offices were instituted for lending money at a moderate rate of interest. In religious matters Alexander preserved an open mind. In his private chapel he had busts of Orpheus, Abraham, Apollonius of Tyana and Jesus Christ. It is said that he was desirous of erecting a temple to the founder of Christianity, but was dissuaded by the pagan priests. There is no doubt that, had Alexander's many excellent qualities been supported by the energy and strength of will necessary for the government of a military empire, he would have been one of the greatest of the Roman emperors.
See Lampridius, Alexander Severus; Dio Cassius lxxviii. 30, lxxix. 17, lxxx. 1; Herodian vi. 1-18; Porrath, Der Kaiser Alex. Sev. (1876); Pauly-Wissowa, Realencyclopadie, ii. 2526 foll. (Groebe); monograph by R. V. Nind Hopkins, Cambridge Historical Essays, No. xiv. (1907).
Initial text from 1911 encyclopedia -- Please update as needed
Maximinus Thrax (235 - 238)