During the long reign of Theodosius II (408-450), the Huns had become a real threat to the heartland of the Eastern Roman Empire. Raids began in 441, in Pannonia as well as along the Danube, staved off only by Constantinople's consent to paying more tribute to the Hun leader Attila. In 447, Hun armies returned to imperial lands, in two simultaneous thrusts. While one went directly to Constantinople, the other thundered through Macedonia, as far south as Thermopylae in Epirus. Though the capital's walls prevented Hun penetration, the Huns did defeat an imperial army near Gallipoli. Attila extracted yet another increase in annual tribute from Theodosius, who died in 450.
Theodosius had produced no male heir, so his daughter Pulcheria married Marcian, a senator and retired officer from Thrace. Seen as unobjectionable by Constantinople elites, he was accepted as Emperor in 450. Aware that Attila was planning a western expedition, one of Marcian's first acts was to refuse the former's demand for more tribute. This was wildly popular, and the East was spared further Hun depredations when Attila led his hordes to Western Roman lands. The remainder of Marcian's rule (d. 457) was filled with religious disputes. Given his role as protector and de facto manager of the Church in the East, the Emperor could not avoid involvement.
The dispute which erupted in the early 450s was similar to the Arianism controversy of the 300s in that involved the nature of Christ and his relationship to the other parts of the Trinity. Back in 448 the cleric Eutyches had been accused of spreading the doctrine that Christ was not bot human and divine. Rather, being more powerful than human, Christ's divinity had overpowered his mortality. Thus, Christ possessed only a single nature. This made sense given Hellenistic philosophical assumptions of the East. This was called Monophysitism, and after its proponents appealed to friendly bishops as well as the Pope Leo I, it became an expanding crisis in the Christian world. In 451, the Fourth Ecumenical Council was held at Chalcedon. Including nearly 600 bishops, the council condemned Eutyches again (he had been previously reinstated) and articulated the Chalcedonian Definition: Christ was held to possess one person and two natures, "unconfusedly, unchangeably, indivisibly and inseparably" united. Though satisfactory in the West and to most Eastern clerics of the time, it made little sense to several clerics and laymen in Egypt, Syria, and other areas. Thus, Monophysitism continued in these areas, invigorating Nestorianism in the Levant as well as Coptic Christianity in Egypt. At times these regions would express their religious difference through separatism. Another noteworthy aspect of the Council was a decree that henceforth the Bishop of Constantinople would be a Patriarch, second only to the Rome Pope in the Christian hierarchy. In future years this led to an Eastern interpretation that Papal supremacy was purely nominal, with eastern provinces responsible to the Constantinople Patriarch alone. Church schism would ultimately result.
Again, in 457 there was no male heir, and no imperial candidate from the Theodosian line stretching back to the 370s. Stepping into the gap as emperor- maker was the Arian Alan serving as Master of Soldiers, Aspar. As both his religion and ethnicity were increasingly offensive to Eastern Romans, he remained the power behind the throne, appointing his household steward as Emperor Leo I (r. 457-474). The new Emperor soon chafed at Aspar's tutelage, and also sensed growing popular resentment against Germanic prevalence in the army especially. Leo thus decided to purge the military of Germans, and the remainder of his reign was occupied with the struggle against Aspar and his colleagues. These included Basiliscus, Leo's brother-in-law, who while a Hellenized Roman devoted to Monophysitism, shared in common with the adept yet Germanic general a hatred of the Emperors new allies. These were mostly Isaurians, battle-hardened mountain tribes from beyond the Taurus ranges in Southeastern Anatolia. Leo was particularly close to an important chieftain, Tarasicodissa Rousoumbladeotes, who modified his name to Zeno upon marrying Leo's daughter Ariadne.
Sparring between the two camps began in 468. Leo decided to launch a large- scale expedition against the Vandals in North Africa, and Basiliscus arranged his own command of it, to position himself for eventual imperial rule. After landing, however, Basiliscus did not take advantage of early victories by subordinates, and allowed Vandal leader Gaiseric to trick him by false offers of surrender. Instead, the Vandals prepared a fleet of fire-boats, with which they incinerated the Byzantine fleet. Basiliscus fled the scene prematurely, and was forced to seek refuge in St. Sophia in Constantinople. Aspar as well was tainted by the defeat. Attempting to even the scales, in 469 he plotted an assassination of Zeno, yet was thwarted at the last moment. In 471 his son Ardabur even tried to woe Isaurian clans away from Zeno. His patience exhausted, Leo had Aspar and his son killed the same year by palace guards.
Leo died in 474, having assured his people a spell of Orthodoxy and comparative peace. He had appointed as his successor his grandson and Zeno's son, Leo II. Ariadne prevailed upon the latter to immediately elevate Zeno to co-Emperor. Nine months later Leo died, and Zeno became sole ruler (474-491). His first measure was to negotiate a peace with the Vandals, who henceforth no longer threatened Byzantium. He spent the next decade dealing with severe challenges to the throne. Basiliscus and Ariadne's mother Verina were still the chief initial antagonists. Joining them was Illus, an Isaurian general whose motives are mysterious. With him, they appeared to gain the support of certain influential senators and segments of the population opposed to Isaurian presence on the throne. At the end of 475, Zeno felt sufficiently threatened to flee Constantinople for the Taurus mountains. Basiliscus appeared to realize his ambitions when he was subsequently proclaimed emperor. His rule until 477 was a disaster. The masses were alienated through harsh taxation, while the Church despised him for trying to impose Monophysitism in the Empire, going so far as to abrogate the Council of Chalcedon. Seeing public disaffection from Basiliscus, Illus returned to Zeno, readying him for a counter-attack. Basiliscus was finally undone when he made his own nephew Harmatius Master of Soldiers. A delusionary hedonist, he was easily persuaded to support Zeno by promise of government advancement. Thus, in 477 Zeno returned as Emperor, and Basiliscus was exiled to Cappadocia.
For the rest of his reign, Zeno had no rest. He had Harmatius murdered so as to avert what could have been a threat to his rule. In 479, he had Verinus imprisoned for similar reasons. Another Marcian then revolted, and got as far as storming the palace before Illus brought in Isaurian contingents. Ironically, Illus himself revolted again from 483. Partly, this was due to the many attempts on the latter's life emanating from close to the throne. In 477, an imperial slave had tried to kill him; in 478 an agent of Verina was similarly found. In 482, Ariadne sent a would-be assassin as well. Also, Zeno was in danger as long as another powerful general was near. In 484 the Emperor denounced Illus after he quarreled with Zeno's brother in Syria as to how to put down a rebellion. Illus then joined the rebel, moving to Tarsus. At this point, Zeno elected to use the Ostrogoths, who had been intermittently raiding Thrace and the Balkans. Their leader Theodoric agreed to lead an army against Illus. Defeated at Antioch, the rebels retreated to Isauria and were eliminated by 488. Zeno was then able to convince Theodoric to take his Goths out of the Eastern lands entirely, and go to Italy to unseat Odovacar who had been ruling in the Emperor's name since 476.
The final years of Zeno's rule were filled with religious problems. His attempt to affect a Monophysite-Orthodox compromise failed, as saying that Christ was both God and man, without referring to his actual constitution, satisfied no one. The Pope Felix III was particularly offended when the Emperor and his patriarch Acacia consented to a Monophysite's appointment to the Patriarchate of Alexandria. The Pope excommunicated Acacia, who returned the favor, beginning a schism that lasted the next thirty-five years.
In 491, Anastasia became Emperor. Five points are worth noting: 1) He was an exceedingly thrifty ruler, who while leaving the imperial fisc in better shape than he found it, bored and disaffected the populace with his dour, puritanical attitudes; 2) though appearing Orthodox at first, his Monophysitism became more pronounced, especially after 510. This widened the schism with Rome, and caused threatening street-brawls in the capital between partisans of the two creeds. 3) Zeno's brother, Longinus, felt passed over for the throne, and thus caused trouble by gathering a large group of mostly Isaurian supporters who also caused street riots. In 492, Anastasius had Longinus exiled to Egypt, whereupon full-scale civil war started in Constantinople. While peace returned here the next year, only in 496 did Anatolia quiet down. 4) The populace began to divide more and more into two factions, the Blues and Greens, based originally on charioteer teams in the capital. The groups had important urban defensive roles, such as policing and guarding the walls in major cities. Blues were somewhat allied with Greco-Roman landholding aristocrats and supported the Chalcedon doctrine on Christ's nature. The Greens found support among urban traders and the civil service, and contained Monopysite sympathies. From the mid-490s they began to riot against each other, with the Emperor often entangled. This at times linked up with the religious controversies. 5) From the 510s, foreign threats resurged. The Sassanians began a three-year war during which they took several important eastern defenses, while the Bulgars began to penetrate Thrace and raid during the same years. In 518, the Thracian peasant and general Justin succeeded Anastasius. Aside from sending initial expeditions against the Ostrogoths in Italy, he ended the Rome-Constantinople schism, and was scrupulously Orthodox. He also continued to suffer the Blue- Green disturbances, advocating for the Blues. His guide in all things was his nephew Justinian, whom he made Master of Soldiers.
This period, witnessing the fall of Rome in the West, also presented trends that would come to characterize Eastern Roman political life, such that a particularly 'Byzantine' formation was emerging. First was the incessant descent upon Byzantium's Danubian borders of Barbarian masses no longer interested in becoming part of the Empire, but in either plundering it or colonizing it. Ostrogoths were ephemeral in this respect, and would be replaced by Avars, Bulgars, and Slavs into the tenth century.
Second, Constantinople would very rarely witness smooth imperial succession. A dynamic emerged whereby A) an external crisis would combine with B) a politicized population and C) individual elite's ambitions stoked by D) royal family members (often female) to cause at times dizzying successions of would-be rulers. In every case, however, an experienced administrator or general would jump into the breech, preventing total decomposition. In this context there evolved an elite circulation, not of design, but of necessity. This is the third issue. Gradually, Eastern Rome was becoming less Roman in leadership and more representative of its multi-ethnic population, including Isuarians, Greeks, Armenians, and Balkan masses. Of course, underneath it all, Byzantine bureaucracy and administration would provide governing continuity, so that repeatedly, state and society would find the resources to continue.
A fourth characteristic is the state's involvement in determining theological policy. Eastern Roman emperors styled themselves after Constantine (r. 313-337). He had patronized and managed the Church, embodying the state-society- religion unity so dear to the Roman mind. Later emperors would try to do the same. It was almost impossible for the Orthodox Church in Constantinople, Alexandria, Antioch, or even Jerusalem, to establish an autonomous space, in terms of theology, administration, or even in fiscal matters. Only monasteries were somewhat untrammeled, and in the eighth century, they too would find it difficult to remain beyond state monitoring. The consequences of such an approach were mixed. On the one hand the religious aspect would at times grant added legitimacy to emperors. At times, external conflicts could be portrayed, with no dissimulation, as wars for the survival of Christianity as represented by the state. As well, being able to avail themselves of the Church's administrative powers was quite helpful, just as in later times the Church's held could entail a welcome financial windfall.
On the other hand, it was at times impossible for the Church in Constantinople to hold the moral high ground when directed by an unpopular, or assumedly unethical Emperor. From the ruler's perspective, control of the Church was potentially problematic in that clerics could act as a focus for effective political dissent, especially if allied to a rival imperial claimant. Beyond that, close patronage of the Church dragged Emperors into doctrinal disputes, as they were the last theological resort and could not remain aloof from those conflicts between patriarchates with ramifications for social order and political stability. This entanglement in turn made it all too easy to alienate the Catholic Church in the West. Emperors had still not written off the West and their presumed suzerainty over its church. The combined affect of all the continuing religious disputes, however, was to injure the feelings of the Pope, and loosen the East-West bonds on this score. Finally, even the losers of theological disputes hurt the power of the Emperor and state. Repudiated doctrines did not go away; rather, they became the rallying cry, or even local creed, of key regions in the Empire, such as Egypt and sections of Syria. With persistent foreign invasions on all fronts, it was perilous indeed for large numbers of subjects in strategically vital areas to be politically and religiously alienated from the center.