Dr. David Gwynn

Whereas Diocletian starts it in 303, but abdicates in 305.

He abdicates as an emperor.

And voluntarily stands down, as does Maximian.

Although we get the distinct impression Maximian didn't want to, and Diocletian didn't give him the choice.

What we just don't know is whether this was built into the original Tetrarchic agreement.

After all, the basic problem with the Tetrarchy is what happens if, say, the juniors decide they don't want to be juniors anymore.

How do you control the ambition, prevent a civil war?

What seems to have been agreed, we just don't know exactly when, is that at a certain point, the two seniors will stand down, the two juniors will become seniors, two new juniors will be appointed.

And so the cycle could repeat.

It ends up being, effectively, Diocletian reaches 20 years in power and then begins the abdication process.

Whether it was agreed when the Tetrarchy came into shape in 293, we don't know that.

But certainly that's what happened in 305.

Diocletian and Maximian stand down.

Maximian will launch an attempted coup to come back, that's why we're pretty sure he didn't want to, and will end up being killed in the next couple of years.

But it says a lot about Diocletian we don't know when he died.

Basically, he abdicates.

He had a palace built for himself at Split on the Adriatic coast.

Sadly, heavily damaged in the Balkan conflicts of the last 30 years.

But a magnificent palace.

That's where he went.