Justinian I was the most well-known of the rulers of the Byzantine Empire, the Eastern Roman Empire. His influence in military successes was felt for quite some time, and his influence in legal matters was widespread and lengthy.

He was born Petrus Sabbatius in 483 in Tauresium, in Dardania, what is now Yugoslavia. His uncle, Justin, became emperor in 515 and adopted Petrus about the same time. Petrus thus became Justinianus, or just Justinian. His education, as the nephew of the emperor, included Roman history, theology, and the law.

In 521, Justinian was named consul and army commander. He took the army to war in 526, fighting against the Sassanian Empire over what is now the country of Georgia. A year later, he became emperor, when his uncle died.

Justinian had married Theodora, a dancer, in 525. She was not at all of the aristocracy, as he was, yet they married all the same and he came to value her counsel. They had no children.

One particular example of her dedication to his cause was during an uprising in January 532. Justinian was quite a fan of chariot racing, as was the general populace. During one particular race, the fans of both two normally opposing factions banded together and rushed the royal box, seemingly intent on harming the emperor. He retreated to the royal palace and, fearing for his life, made plans to abdicate and flee. Theodora refused to leave and implored him to stay as well. He did so, and his troops quelled the riot.

He had some of the ringleaders of the riot executed. The rioters had taken their disturbance to the streets and damaged some of the city. The emperor took the opportunity to rebuild Constantinople; among the new projects was the famed Hagia Sophia, damaged in the riots and rebuilt to a much grander extent afterward. He ordered construction projects galore, including a network of underground cisterns in Constantinople.

The war with the Sassanid Empire ended in 532 with a victory achieved by the Roman general Belisarius (left). Justinian, through this general, then set about reconquering lands once owned by the Empire.

Targeting the Vandals, Belisarius took an army of 15,000 men into North Africa and "liberated" it, establishing an African prefecture at Carthage. During the next five years, Belisarius and his troops conquered the Ostrogoths and rolled back their occupation of Italy.

In the same year that Rome found a new (and, at the same time, old) ruler, 540, Belisarius had to sail back eastward and re-engage with the Persians. A plague outbreak stalled the fighting between the two powers, which ended with another truce in 545.

At the same time, the Ostrogoths had thrown off the Roman yoke and attempted to reassert their authority in Italy. They were successful for a time but lost their hold on the area again, thanks to the determination of the Roman armies. This time, it was the general Narses who was able to turn the tide in Justinian's favor, defeating the Ostrogoths under Titila at Busta Gallorum in 552. Two years later, the Romans had to contend with an invasion of the Frankish army and were again successful.

Rounding out Justinian's reconquests was a bit of Hispania. By 555, the amount of land controlled by the Roman Empire (for it wasn't until later that this entity was called the Byzantine Empire) approached what it had been in the heyday of expansionist emperors like Trajan.