During the Crisis of the Third Century, two breakaway empires were formed from territory controlled by the Roman Empire. These two empires were the Palmyrene Empire in the east and the Gallic Empire in the northwest. They both broke away from the Roman Empire during the reign of Gallienus. Gallienus ruled throughout much of the middle period of the Crisis of the Third Century and, in spite of his best efforts, was unable to prevent the splintering of the Roman Empire and incapable of leading the reunification movement.

Queen Zenobia was a ruler of the short lived Palmyrene Empire during the Crisis of the Third Century. She led a revolt (along with her husband) against the Roman Empire and helped form the Palmyrene state. She then led the conquest of Egypt (after her husband’s death) and ruled for a few years before she was captured by Aurelian and held hostage. Her empire would swiftly be reabsorbed into the Roman Empire.

The Palmyrene Empire was one of two breakaway empires of Rome which were formed during the Crisis of the Third Century (the other was the Gallic Empire). The Palmyrene Empire was situated in modern-day Syria, Egypt, and Asia Minor. It successfully defended Roman territory from the Sassanid Empire, but was eventually conquered by Aurelian and reabsorbed into the Roman Empire.

Alexander Severus was murdered, triggering the onset of the crisis. There were multiple plagues and the militia began ruling who would take the throne. It is easy to rule out the option that the economy was running well because this would not have triggered a crisis. Also remember that church and state were not attempting to separate at this time in the Roman Empire. The tricky part here is choosing whether famine was the main cause of the Crisis. However, looking to the facts we know that when Alexander Severus was murdered order in the empire fell rapidly leading to the onset of the famous crisis. 

The Battle of Emesa was fought in 272 CE between the forces of the Roman Empire, led by Aurelian, and the forces of the breakaway Palmyrene Empire. It ended in defeat for the Palmyrene Empire and allowed Aurelian to conquer and unify the Palmyrene Empire with the rest of the Roman Empire.

The Battle of Naissus was fought in 268 CE, between the forces of the Roman Empire (led by Gallienus) and an alliance of Gothic tribes. It was fought at the height of the Crisis of the Third Century and the victory of the Romans would prove something of a turning point in the crisis. The Romans completely annihilated the Gothic army and largely removed the threat of Germanic barbarian occupation of the Roman Empire (at least for a generation or two).

The Battle of Chalons was fought in 274 CE, during the later years of the Crisis of the Third Century. The battle ended in victory for the forces of the Roman Empire, led by Aurelian, and defeat for the forces of the Gallic Empire, led by Tetricus. The battle resulted in the end of the Gallic Empire and its absorption back into the Roman Empire.

Valerian and Gallienus were two of the most notable emperors during the Crisis of the Third Century. Valerian, and his son Gallienus, were declared co-emperors in 253 CE and worked tirelessly to reunite and rebuild the Roman Empire. Their work, however, was ultimately unsuccessful; Valerian was captured by Sassanid forces in the Middle East and Gallienus was assassinated by a rival claimant to the throne

The Battle of Edessa, fought in 260 CE, was the first battle in which a Roman Emperor was captured by the forces of the enemy. The emperor in question was Emperor Valerian, who ruled during the turbulent period known as the Crisis of the Third Century. After Valerian’s capture, his son Gallienus ruled as the sole Emperor.

The Battle of Margus was fought in 284 CE, between the forces of Diocletian and the forces of the Emperor Carinus. The battle ended in victory for Diocletian and allowed him to take control of the entire Roman Empire. The Battle of Margus is one of the last battles of the Crisis of the Third Century, as shortly thereafter Diocletian was able to enact a series of reforms which temporarily strengthened the Roman Empire.