Flavius Theodosius (10 April, 401 – July 28, 450), called the Calligrapher, known in English as Theodosius II, was an Byzantine Emperor (reign 408-450), mostly known for the law code bearing his name, the Codex Theodosianus, and the Theodosian Walls of Constantinople (modern-day Istanbul) built during his reign.
The eldest son of Aelia Eudoxia and Byzantine Emperor Arcadius, Theodosius was heavily influenced by his eldest sister Pulcheria, who pushed him towards Trinitarianism. Pulcheria was the primary driving power behind the Emperor and many of her views became official policy. These included her anti-Semitic view which resulted in the destruction of synagogues. He ordered the execution of Gamaliel VI, the Nasi of the Jewish Sanhedrin in 425 for authorizing the building of new synagogues, and abolished the office.
On the death of his father Arcadius in 408, Theodosius became Emperor. Because of his minority however, real power was exercised by the praetorian prefect of the East Anthemius until his dismissal in 413. It was under Anthemius' supervision that the Theodosian land walls of Constantinople were constructed.
In June 421, Theodosius married the poet Aelia Eudocia. They had a daughter, Licinia Eudoxia, whose marriage with the Western Roman Emperor Valentinian III marked the re-unification of the two halves of the Empire, even if for a short time. Theodosius created the University of Constantinople, and died in 450 as the result of a riding accident.
On the death of the Emperor Honorius in 423 AD the primicerius notariorum Joannes was proclaimed Emperor. After some deliberation in 424 Theodosius II began a war against Joannes which ended in May 425 when Valentinian III was installed as Western Emperor.
Much of the next 15 years was peaceful with short Hun raiding attacks. For that peace the Eastern Roman Empire paid tribute to the Huns which amounted to 350 Roman pounds (ca. 114.5 kg) of gold until 434 and 700 Roman pounds after that.
Peace ended in 440 after the fall of Roman Africa to the Vandals. For its reconquest both Eastern and Western Empires sent forces to Sicily from which they launched attack on Carthage, but this project failed. Seeing the Imperial borders without significant forces, the Huns and Persia declared war. During 443 two Roman armies were defeated and destroyed by the Huns. In the subsequent peace agreement Roman tribute was tripled to 2,100 Roman pounds (ca. 687 kg) in gold after which the Huns withdrew into the interior of their Empire.