Dr. David Gwynn

In some ways, Diocletian is a bit luckier than talking about the third century crisis might sound.

During the worst years of the 3rd century, which is above all the 250s and 260s, the Roman Empire was in severe danger of completely shattering.

Different regions broke away, in particular Britain and Gaul break away into their own miniature Gallic Empire.

Likewise in Syria, the Palmyran Empire takes away the eastern territories.

It really does look like the empire could be completely collapsing.

But in the later 260s and the early 270s, it all got pulled back together, above all by the emperors Gallienus and Aurelian.

So the empire has been pulled more or less back into its traditional shape.

So it extends from Hadrian's Wall in Britain, down to the Zara Desert in Africa, out towards the Euphrates River in the east.

So Diocletian has actually inherited an empire that is in a little better state than had this been 20 years earlier.

That being said, all the frontiers remain uncertain.

The Persians are still a major threat to the east, as they have been right through the third century.

There's turmoil on the Rhine and Danube.

And obviously, if you come to power through what does look like a combination of usurpation, assassination, and a few skirmishes, you're going to face rivals.

So it's internally very unstable and externally threatened.

Diocletian is clearly a pragmatic and highly intelligent ruler.

That will come very clear right through his reign.

And one thing that has become very obvious across the third century is the Roman Empire is too big for one man to easily control.

If everything's stable, then fine, you can have a single emperor as the focus of authority.

But if you've got trouble in Britain, and on the Rhine, and on the Danube, and on the Euphrates with Persia, possible revolt in Egypt, one person cannot deal with all that.

Diocletian needed to delegate.