THEODOSIUS II
401 - 450

Theodosius was Eastern Roman emperor from 408 - 450.

Theodosius' father was Eastern Roman emperor Arcadius. Theodosius II's grandfather was Theodosius I, the father of Arcadius.
 

Theodosius was busy fighting the Vandals and the Huns, who were led by Attila at the time.

395 - Final division of the Roman empire between Arcadius and
Honorius, the two sons of Theodosius I. The Goths revolt, and
under Alaric attack various parts of both the Roman empires.

In 413, Theodosius fortified Constantinople by building a major wall around the city. Here is the map:
 

Constantinople's Wall by Theodosius II
Click map to enlarge