Theodosius the Great, Emperor: 379-395

The Valentinian dynasty had four emperors overlapping in power over nearly three decades—Theodosius married a Valentinian princess (like Gratian married a Constantian princess), but his sons were from an earlier marriage. Like Diocletian, Valentinian I divided power with his brother Valens at the beginning of his reign, rather than just leave it for his children to share, as Constantine (and later Theodosius) did. I was troubled by Zosimus' explanation for Valentinian choosing his brother: "whom he thought most likely to prove faithful to him" (Book 4, p. 66). After two and a half decades of fighting and squabbles among the sons and nephews of Constantine I, all of which Zosimus had just been writing about, I should have no expectation of imperial fraternal affection. Yet, even despite their religious differences, Valentinian proved corrected enough in his choice.

Valentinian I died of apoplexy (Ammianus Marcellinus XXX.6 is the best source), which I take to be a natural cause even if there might be environmental and emotional factors of significance.

When Valens died at the battle of Adrianople, Gratian appointed Theodosius to become emperor of the East, and he had some quick success in battle against the Goths, securing his borders, and most importantly Constantinople, against the Goths (Orosius VII.34, Zosimus p. 76-81, Jordanes 27). Theodosius followed this up with some well executed diplomacy with the Gothic king Athanaric (Orosius VII.34, Zosimus p. 81, Jordanes 28).

When Gratian was killed by the usurper Maximus (and Valentinian II exiled), Theodosius mustered his forces to—eventually—fight back to remove Maximus from power and restore Valentinian II.

When Valentinian II was killed by Arbogastes and Eugenius came to power, Theodosius again prepared for war and crossed the Alps to fight against illegitimate power. In the battle, Eugenius was taken and killed, while Arbogastes fled to the mountain wilderness in fear and committed suicide. Theodosius marched in triumph to Rome, and died soon after in his journey back to Constantinople according to Zosimus, or while in Milan according to Orosius.

From the death of Valentinian in a de jure sense, and from Eugenius' death in a de facto sense, Theodosius held dominion over the entire Roman Empire. He was the last. He died almost exactly 400 years after the mid-point of Augustus' principate, and it is surprising how well Theodosius's power compares to Augustus':

• The borders of the empire were nearly identical. The Rhine, Danube, and Mesopotamia were fluid. Theodosius' claim on southern Britain (now England and Wales) was much stronger. Certainly the fighting with the Germanic peoples was more defensive for Theodosius than Augustus, but he is hard to call less successful.
  
• Both gained power over the whole empire following multiple civil wars. Theodosius' wars were smaller, which I suppose could just mean that all the Roman armies were weaker in the fourth century than in Augustus' (then Octavian) time, but they were also less destructive.
  
• Augustus was very concerned with succession, and often disappointed as his favorites died (having no sons himself), until he was finally left with his step-son Tiberius. Theodosius had two sons to whom he left the empire.
  

Of course, the time of Augustus was similar to the previous generation or three, that I commented on from Orosius. Rome was much more dangerous to itself in those days; by Theodosius' time, its external enemies were much stronger (or maybe just more motivated by fear of a third entity like the Huns). On the other hand, provinces like Gaul, Syria, and Egypt were probably much better integrated after another 400 years-again like Orosius commented.

I will write more about the religious developments of the time period in my next post.