During the middle of the 3rd century (crisis years) the roman legions seemed to be beaten left and right by the Goths, Sassanians and numerous Germanic tribes. Then suddenly with the arrival of the Illyrian emperors (Claudius II, Aurelian) a few years later they barely lost a battle.

Militarily speaking: What happened?


2 Answers 2


The Premise is a bit off here. During the Crisis of the 3rd Century as well as after, the Roman army usually could win a set-piece battle over barbarians or the Persians. The difference was that the Roman army usually wasn't around where these incursions happened, and the tribes could run amok without much opposition.

With the distractions of the Civil Wars, the armies were often off dealing with succession business rather than remaining close to the border. If an emperor tried to move back to a frontier, often he was deposed. And if he was on one frontier, the others had nobody.

Ironically, the first turn of the tide was the 'secession' of the Gallic Provinces and the East under Odenathus and Zenobia. These new 'emperors' marshaled the local forces much like the Emperor might have, but now there were three at the same time. This is were you started to see an improvement against the invaders, as each sector could concentrate on one area and start to make headway.

The Illyrians then gave some superior leadership that began to make inroads into the indiscipline of the army (although with some setbacks as Aurelian was murdered by officers). This and the improved frontier situation allowed the Empire to be rather easily reunified by Aurelian, as the breakaway provinces really didn't want to destroy the Empire.

This same solution was used by Diocletian with the Tetrarchy - having 4 emperors at once allowed each to readily respond to frontier threats. It worked well as long as Diocletian was around to be the unifying force, but broke down after that.


Before the Illyrian emperors there was a lot of internal conflict. The borders of the empire were constantly weakened by troop moving on other Romans. This caused invasions of the enemy tribes who believed at that time it was opportune to invade the empire.

Only when the empire was temporarily split in west and east that some stability was formed again. This focussed the defences on the east and west border without any inteference.

  • 1
    Both Claudius II and Aurelian seemed to be constantly fighting battles internally,in the east and the west, even more so than their predecessors. Yet the Illyrians almost always crushed their opponents while Gallienus, Valerian, Decius and others struggled terribly. Was it simply down to better leadership , some change in military structure or something else?
    – Karlth
    Apr 15, 2014 at 12:00
  • 1
    This goes some way towards being an answer, do you have any references?
    – Kobunite
    Apr 15, 2014 at 12:09
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    Valerian was captured during a truce conference, not by losing a battle.
    – Oldcat
    Apr 15, 2014 at 21:48

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