After the assassination of Commodus, the Roman legions began to propose their candidates and a state of chaos dominated throughout the Empire, until Septimius Severus beat Pescennius Niger. Severus visited Egypt and ordered the restoration of the city council (Boule), not only in Alexandria but also in all the capitals inside Egypt. Antoninus (Caracalla) continued the calm politics of his father and decided to give the Roman citizenship to all of the Empire's nations. But when Caracalla visited Egypt, he did not like the fact that the Alexandrians were fans of irony and criticism. Therefore, he ordered his troops to punish them, which in return caused a lot of destruction. Post-Caracalla period witnessed a fighting among the Roman generals over the succession until Diocletian. During this period, Egypt was no longer important to the Roman Empire because of the impoverishment and depletion of it resources. Egypt became even the destination of the repudiated by Rome. Zenobia, the wife of Odenathus (the late governor of Palmyra) invaded Egypt with an army of 70000 soldiers.
In Alexandria, her army declared his son, Vaballathus, emperor. Aureliano recognized Vaballathus as a partner, but very soon the war broke out between them and the former was able to conquer Palmyra and captivate Queen Zenobia. In the meantime, a new different threat appeared. The new Christian Religion which predicated fraternity and redemption, spread in Egypt and in many other provinces of the Empire. The Egyptianized Greeks easily adopted the new religion believing that it had much resemblance with their Holy Trinity and its values represented by redemption, salvation, resurrection, passive resistance, and equity between humans.
Diocletian (284 - 305)
In addition to poverty, high taxes and unjust discrimination, Egypt also suffered from the attacks of the Blemmyes who came from the South. The Egyptian people did not show any resistance to these tribes, perhaps because they were tired of the Roman occupation. During the decline, the Roman administration did not find soldiers who wanted to serve in desert sites deprived from any sign of civilization. Diocletian decided to move the defensive line to Aswan and convinced Bedouin tribes to move to the South to defend the Southern border in exchange for financial support. Moreover, Diocletian tried to buy peace through giving the Blemmyes large sums of money on the condition that they abstained from looting and pillaging.
In Alexandria, revolutions erupted one after another, the strongest of which was headed by Lucius Domitius Domitianus, who was declared emperor. Diocletian sent a large force that besieged Alexandria for 8 months and then attacked the city causing a great destruction.When Diocletian came to Alexandria, he found it an impoverished destroyed city with diseases and plagues striking its peoples. Diocletian decided to buy the Alexandrians' loyalty decreeing that part of the city's wheat reserve was to be donated to satisfy their hunger. In appreciation, the Alexandrians erected a monument in the form of a 26-meter column. Diocletian decided to cancel the Alexandrian currency. Thus Egypt became incorporated with the monetary system of the Empire. Diocletian had to face the danger of the new Christian Religion, which put obstacles in the way of materializing his project to revive the Empire.
Christianity had spread in the Delta among the Greco-Egyptians and gradually spread to Alexandria that was evangelized by St. Mark in 60 AC. In 68 AC, he was martyred by an attack of pagans. Diocletian ordered the persecution of Christians and massacred thousands of them, so the year of his coronation is considered the year of the martyrs and the beginning of the Egyptian Coptic Calendar. Diocletian divided the Empire into four regions, each two regions were governed by an emperor.
Constantine (307 - 337)
Constantine had defeated Lucinius in his war for the Eastern Empire and chose the city of Byzantium to be his capital in 323 AC. Constantine recognized Christianity as an official religion of the Empire, in an attempt to appease the Eastern Empire. But very soon, differences among Christians broke out over determining the relationship between members of the Holy Trinity and wars broke out again, this time religious. Constantine held a forum in Nikaia in 325 AC to bridge differences between Arius and Bishop Athanasius of Alexandria. The consequences of the forum were disastrous because, initially Arius went into exile and, then Athanasius. These actions sowed divisions among the Eastern churches and sparked a conflict between the state that wanted to control the church and the church that claimed the old privileges of ancient pagan temples.