Sometimes usurpers would call themselves Caesar to try and appease the ruling Emperor. "I'm not really after your job, I'm just helping you out see. I'm totally just a Caesar."

Although that was later under the Tetrarch when the distinction was made by Diocletian.

Locking this down because some of you can't behave.

Fucking waste of ammo.

I've been on this Reddit a while....

I'm just going to leave this link here.

https://en.m.wikipedia.org/wiki/Migration_Period

That also means that Septimus' 1900 year old propaganda move is still working.

In order to legitimise his reign, after the year of the the five Emperors, Septimus Severus announced that he was actually the adopted son of Marcus Aurelius. And to honour his 'father' he named his first born son after him and his 'grandfather'.

There's a reasons everyone calls him Caracalla, Marcus Aurelius II doesn't have quite the same ring to it.

So the Romans did campaign along the Rhine for a very long time. You have Julian's Campaigns as Caesar against the Alemanni, and his successor Valentinian and Gratian campaigned along the Rhine.

The only problem was after that period, the Gothic War drew Roman military power towards the Balkans and the majority of Roman Gaul was left under the protection of the Franks.

However once the barbarian invasions of the early 400s happened. The empire in the West was too busy dealing with that to engage in campaigns into Germania.