Alexander himself was eventually assassinated, and his death marked the beginning of the events of the Crisis of the Third Century, which included nearly fifty years of civil war, foreign invasion, and the collapse of the monetary economy.

This alienated many in the Roman army, leading to a conspiracy that resulted in the assassination of Alexander, his mother Julia Avita Mamaea, and his advisors.

[11] Alexander's grandmother Maesa believed that he had more potential to rule and gain support from the Praetorian Guard than her other grandson, the increasingly unpopular emperor Elagabalus.

[13] The Roman army hailed Alexander as emperor on 13 March 222, and the Senate ratified this the following day, conferring on him the titles of Augustus, Pater patriae and Pontifex maximus.

[14] Throughout his life, Alexander relied heavily on guidance from his grandmother, Maesa, before her death in 224, and mother, Julia Mamaea.

He extended the imperial residence at the Horti Lamiani on the Esquiline Hill with elaborate buildings, and created the Nymphaeum of Alexander (known as the Trophies of Marius), which still stands in the Piazza Vittorio Emanuele.

[21] Additionally, during his reign taxes were lightened; literature, art and science were encouraged;[22] and, for the convenience of the people, loan offices were instituted for lending money at a moderate rate of interest.

According to the Historia Augusta, he wished to erect a temple to Jesus but was dissuaded by the pagan priests; however, this claim is unreliable as the Historia Augusta is considered untrustworthy by historians, containing significant amounts of information that is false and even invented, extending to when it was written and the number of authors it was written by.

Alexander could not openly punish the ringleader of the riot, and instead removed him to a nominal post of honor in Egypt and then Crete, where he was "quietly put out of the way" sometime after the excitement had abated.

[33] Different reasons are given for this issue; Campbell points to ...the decline in the prestige of the Severan dynasty, the feeble nature of Alexander himself, who appeared to be no soldier and to be completely dominated by his mother's advice, and lack of real military success at a time during which the empire was coming under increasing pressure.

[33]Herodian, on the other hand, was convinced that "the emperor's miserliness (partly the result of his mother's greed) and slowness to bestow donatives" were instrumental in the fall of military discipline under Alexander.

[35] In 231 AD, Ardashir invaded the Roman provinces of the east, overrunning Mesopotamia and penetrating possibly as far as Syria and Cappadocia, forcing from the young Alexander a vigorous response.

[40][41] Further losses were incurred by the retreating northern army in the inclement cold of Armenia as it retired into winter quarters, due to a failure through incompetence to establish adequate supply lines.

The soldiers serving under Alexander, already demoralized after their costly war against the Persians, were further discontented with their emperor when their homes were destroyed by the barbarian invaders.

[47] Due to incurring heavy losses against the Persians, and on the advice of his mother, Alexander attempted to buy the Germanic tribes off, so as to gain time.

With the Thracian's hailing came the end of the Severan Dynasty,[50] and, with the growing animosity of Severus' army towards him, the path for his assassination was paved.

[52] Alexander was thus assassinated together with his mother in early March[58] in a mutiny of the Legio XXII Primigenia at Moguntiacum (Mainz) while at a meeting with his generals.

However, Lampridius makes it clear that he is more supportive of an alternative theory, that Alexander was murdered in Sicilia (located in Britain).

A German servant entered the tent and initiated the call for Alexander's assassination, at which point many of the troops joined in the attack.

A large sarcophagus was found inside the tomb in the 16th century, now in the Palazzo dei Conservatori Museum in Rome, was traditionally thought to contain the emperor's remains but this has been disputed.

[61] According to some sources inside the same sarcophagus in 1582 a precious glass urn was found, the Portland Vase, currently on display at the British Museum in London.

[62] After his death his economic policies were completely discarded, and the Roman currency was devalued; this signaled the beginning of the chaotic period known as the Crisis of the Third Century, which brought the empire to the brink of collapse.

[63] Thus, Alexander's taking of his mother's advice to not get involved in battle, his dishonorable and unsoldierly methods of dealing with the Germanic threat, and the relative failure of his military campaign against the Persians were all deemed highly unacceptable by the soldiers.

However, there is no definitive proof that it was found at Alexander's sarcophagus[66] and the interpretations of the scenes depicted are the source of many disputed theories.

[69] According to Historia Augusta, a late Roman work containing biographies of emperors and others, and considered by scholars to be a work of dubious historical reliability,[70] Alexander was also at some point married to Sulpicia Memmia, a member of one of the most ancient Patrician families in Rome and a daughter to a man of consular rank; her grandfather's name was Catulus.

[26][76] The Historia Augusta, a source considered to be generally unreliable, relates that Alexander placed images of Abraham and Jesus in his oratory, along with other Roman deities and classical figures such as deified emperors, Orpheus and Apollonius of Tyana, and prayed there every morning.