Editing Theodosius II (section)

=== Early reign ===
The government was at first administered by the [[Praetorian prefecture of the East|praetorian prefect]] [[Anthemius (praetorian prefect)|Anthemius]], under whose supervision the [[Theodosian Walls]] of Constantinople were constructed.

According to the sixth-century historian [[Procopius]] and eight-century chronicler [[Theophanes the Confessor]], the [[Sasanian Empire|Sasanian]] king [[Yazdegerd I]] (399–420) was appointed by Arcadius as the guardian of Theodosius, whom Yazdegerd treated as his own child, sending a tutor to raise him and warning that enmity toward him would be taken as enmity toward Persia.<ref>[[Alireza Shapour Shahbazi]], [http://www.iranicaonline.org/articles/byzantine-iranian-relations "Byzantine-Iranian relations"], ''[[Encyclopaedia Iranica]]'', 15 December 1990.</ref> Though this story is assumed to be inconclusive, [[Antiochus (praepositus sacri cubiculi)|Antiochus]], a [[eunuch]] of Persian origin, became a tutor and an influence on Theodosius. He also became ''[[praepositus sacri cubiculi]]'' later but Theodosius dismissed him when he reached his adulthood.

In 414, Theodosius's older sister [[Pulcheria]] vowed perpetual virginity along with her sisters. She was proclaimed ''augusta'', and acted as a guardian of her brother. The guardianship ended when he reached his majority, but it is assumed that his sister continued to exert some influence during his reign. In June 421, Theodosius married [[Aelia Eudocia]], a woman of [[Athens|Athenian]] origin.{{sfn|Martindale|1980|p=408}} The two had a daughter named [[Licinia Eudoxia]], another named Flaccilla, and possibly a son called Arcadius.

In 423, the Western Emperor [[Honorius (emperor)|Honorius]], Theodosius's uncle, died and the ''[[primicerius notariorum]]'' [[Joannes]] was proclaimed emperor. Honorius's sister [[Galla Placidia]] and her young son [[Valentinian III|Valentinian]], who had earlier fled to Constantinople to escape Honorius's hostility, sought Eastern assistance to claim the throne for Valentinian, and after some deliberation in 424 Theodosius opened the war against Joannes. On 23 October 425, Valentinian III was installed as emperor of the West with the assistance of the [[Magister Officiorum|''magister officiorum'']] [[Helion (magister officiorum)|Helion]], with his mother taking an influential role. To strengthen the ties between the two parts of the empire, Theodosius's daughter [[Licinia Eudoxia]] was betrothed to Valentinian. She married Valentinian III later on 29 October 437, and became empress of the western portion of the empire.