Why did Justinian rebuild the Roman Empire?

The emperor, known under the name of Justinian I, is probably the best-known ruler of the Eastern Roman Empire and of late antiquity. His reign, which lasted almost 40 years, was marked by the attempt to restore the Roman Empire (Justinian's work of restoration) and at the same time by the transition from the Roman Empire to the Byzantine Empire. He himself was the last Roman emperor whose mother tongue was Latin.

Justinian was born as Flavius ​​Petrus Sabbatius around 482 AD in Tauresium (Macedonia) as the son of a farmer. His uncle Justin was making a career in the army at this time and soon brought Justinian to the capital Constantinople to give him a good education.
After Justin, as Justin I, ascended the Eastern Roman throne in 518, Justinian was gradually built up to become his successor. After Justin's adoption, he was given the suffix Justinianus and made a tremendous career. He soon acted as the emperor's most important advisor and was the official heir to the throne from 525 AD. Because of his rapid social advancement, he was exposed to hostility from the senatorial upper class throughout his life.

After the death of his uncle on August 1, 527, Justinian, as Justinian I, became the new sole ruler of the Eastern Roman Empire. At that time, its area basically extended over almost the same areas as during the division of the empire in 395. However, the Eastern Roman emperors never gave up their claims over the former areas of the west, even after the fall of Western Rome.
However, at the beginning of his term in office, Justinian did not have to devote himself to the West but to the East. There stood a great and powerful enemy with whom Rome had already fought countless wars: the Persian Sassanid Empire. The conflict had become "hot" again a year before Justinian came to power. After several victories (e.g. 530 at Dara) and despite the defeat of Callinicum (April 531), Emperor Justinian had a great victory celebration held in 531 AD. In reality, the conflict ended without a clear winner and was bought by a large payment from the Romans.

Even at the beginning of his term of office, Justinian's strong bond with the Christian faith was evident. He claimed to have received his rule directly from God and zealously promoted Christianization. The closing of the Neoplatonic school of philosophy in Athens in 529 is considered to be one of the striking events that mark the end of antiquity. Presumably the pagan influence of the school was a thorn in the side of Justinian.
In later years his measures for the benefit of Christendom became even more radical: there was persecution of non-Christians, infant baptism was coercive and apostasy was punished with the death penalty. There were also book burnings of "pagan" literature. Only Judaism was officially tolerated, even if its situation deteriorated significantly.
Justinian's measures finally led to the fact that the last parts of the Roman sovereignty of the people were transformed into a strong divine right - a form of rule that was to rule Europe throughout the Middle Ages. Some monarchs in Europe (e.g. Great Britain) still have the addition "by the grace of God" in their title.

Not all people were impressed by Justinian's ideas about empire and so he had many enemies, especially with the senators. The situation only became a serious domestic political problem after Justinian quarreled with the circus parties in early 532. You have to know that the circus parties (racing stables in the Roman Empire) also had increasing political importance, as a large part of the city's population was organized in them.
When the gallows collapsed during the execution of two members of different racing teams, both parties demanded a pardon. Justinian demonstratively refused to speak to the people and thus provoked further tumult. Finally both circus parties united and proclaimed the anti-emperor Hypatius under the battle cry "Nika" (victories). The so-called Nika uprising, in which there was a high probability that several senators were involved, had begun.
Justinian initially saw the situation as lost and thought about fleeing Constantinople. Justinian's general Belisarius finally managed to put down the uprising. A gruesome massacre occurred in the hippodrome, where the insurgents had gathered, which killed around 30,000 people. Hypatius was executed the following day and the uprising ended.

Large parts of the city were destroyed during the Nika uprising, including the Great Church of Constantinople. On February 23, 532, therefore, the construction of a new and larger church began, the appearance of which is said to have appeared to Justinian in a dream. The construction of the "Hagia Sophia", as the building is still called today, should take a total of five years. With its 32 m span and a dome held by only four support points, the Hagia Sophia is still one of the most famous buildings in architectural history. After being converted into a mosque in 1453, it has been a museum since 1934, attracting people from near and far.

Now that the war in the east and the uprising in the interior had ended, Emperor Justinian had the opportunity to look to the west as well. He had long been dissatisfied with the fact that the Vandal Empire (North Africa) had deposed its friendly King Hilderic and replaced it with Gelimer. In 533 AD the imperial general Belisarius therefore advanced with 20,000 soldiers and 30,000 sailors to the west to spark a war. A complete conquest of the Vandal Empire was not even planned at this point, also because the last Vandal campaign (468 AD together with Westrom) had ended in a catastrophe.
To the surprise of the Eastern Romans, the new war was won in a very short time, probably also because the Vandals had many soldiers in Sardinia to put down an uprising. The Romans entered Carthage on September 15, before the last battle could be won at Tricamarum on December 15. Gelimer, who was still able to flee from the battlefield, was captured some time later and finally brought up to a great triumphal procession through Constantinople. In 534 AD, North Africa was again placed under imperial administration as a province. Justinian had won a great victory and was now willing to continue his campaign of conquest.

The next target of the Romans were the Ostrogoths. The empire of the Ostrogoths existed since 493 AD and spanned northern Illyria as well as the entire Italian heartland including the former capital Rome. Justinian recognized his unique opportunity after defeating the Vandals and opened the Gothic War in 535. To this end, attacks were launched on two fronts: in Dalmatia (now Croatia) and in Sicily.
While the war in Dalmatia more or less got stuck, one success after another could be celebrated on the southern front, under General Belisarius: Sicily, Naples and even Rome had been conquered by the beginning of December. At that time, the city of Rome was only a shadow of itself and was again severely shaken by the fighting.
In the period that followed, the war was much more sluggish and devastated large parts of Italy. In 538 the East Romans lost Milan to the Ostrogoths again after a gruesome battle. Famine increased in the countryside and in 539 the Franks invaded northern Italy and fought against both the Romans and the Goths. It was not until May 540 that the Ostrogoth capital city of Ravenna fell and the war seemed to have been decided. General Belisarius, who had the greatest successes of conquest so far, has now been removed from office by Justinian. Previously, he is said to have negotiated arbitrarily with Ostrogoth nobles who offered him the emperor's dignity.

Even before the Gothic War would bring a final decision, the Persians broke the peace that had been negotiated nine years earlier. Whether they just wanted to take advantage of the favorable location, responded to a Gothic request for help or were simply afraid of a revitalized Rome can no longer be clarified without a doubt. In any case, Justinian had to react and move troops from Italy to the east, whereupon the Gothic War subsided for the time being. In Asia Minor the Persians had already devastated Antioch before the Romans could slowly stabilize the situation. Over the next few years, a stalemate developed more and more in the eastern theater of war, even if the war continued until AD 562 and claimed numerous resources.

541 AD was a black year for the Eastern Roman Empire: First the Ostrogoths resumed the fighting and Justinian was in a two-front war, then the Black Death came over the country. Coming from Egypt, the plague reached Constantinople in 542 and continued across the entire Mediterranean region. Justinian himself is said to have suffered from it, but was one of the few to survive it. The disease was later named "Justinian Plague" after him - a dubious honor.

The Gothic War, which was now in its second phase, turned bad for Justinian for the time being. Weakened by the plague and the Persian War, the Eastern Roman Empire lost Naples in 543 and even Rome in 546.
Only when Belisarius was allowed to return to the Italian theater of war did the war seem to fall again in favor of the Eastern Romans. Coming from the south, he lifted the siege of Otranto and marched into Rome in 547. By then the war was already more cruel and bloody than ever. The total devastation of Italy at this time stands, among other things, for the transition from antiquity to the Middle Ages.

In 549 AD the Ostrogoths invaded Rome again, whose population had meanwhile dropped to a few 10,000. The city now resembled a field of ruins. Justinian had now decided to finally recall Belisarius and replaced him with his new general Narses. Fortunately for him, an armistice was reached on the Persian front from 551 onwards, albeit not a permanent one, which freed up more forces for the Gothic War.
With 30,000 men, Narses now advanced to northern Italy and faced the Ostrogoths at Gualdo Tadino, whom he was able to destroy. A short time later he moved into Rome, which was now finally recaptured by the Eastern Romans. In October 552 there was the last great battle of the war on Mons Lactarius, near Naples. After two days of tough struggle, the war was finally decided, even if it took until AD 562 before the last Gothic fortresses were surrendered.

Justinian had achieved in just a few years what no one would have thought possible: In addition to North Africa, he had also recaptured the heartland of the old Roman Empire. In the short term, it seemed as if Rome had returned to its old strength. But appearances were deceptive: Italy was devastated and, for the strained empire, a burden rather than a profit. Although Narses tried to rebuild the infrastructure on behalf of Justinian, time and money were short. Years of war and plague had cost the Eastern Roman Empire numerous resources, and the fighting would prove to be a Pyrrhic victory after Justinian's death. The Lombards invaded Italy as early as 568 AD and were able to absorb large parts of the boot. Justinian himself no longer had to experience the collapse of his restoration work - he died on November 14, 565 in Constantinople.