led by Gordian I and Gordian II, which was soon supported by the Roman Senate, but this was quickly defeated with Gordian II killed and Gordian I committing suicide. The Senate, fearing Imperial wrath, raised two of their own as co-Emperors, Pupienus and Balbinus with Gordian I's grandson Gordian III as Caesar. Maximinus marched on Rome but was assassinated by his Legio II Parthica, and subsequently Pupienus and Balbinus were murdered by the Praetorian Guard. In the following years, numerous generals of the Roman army fought each other for control of the empire and neglected their duties of defending it from invasion. There were frequent raids across the Rhine and Danube frontier by foreign tribes, including the Carpians, Goths, Vandals, and Alamanni, and attacks from Sassanids in the east. Climate changes and a sea level rise disrupted the agriculture of what is now the Low Countries, forcing tribes residing in the region to migrate into Roman lands. Further disruption arose in 251, when the Plague of Cyprian (possibly smallpox) broke out. This plague caused large-scale death, severely weakening the empire. The situation was worsened in 260 when the emperor Valerian was captured in battle by the Sassanids (he later died in captivity). Throughout the period, numerous usurpers claimed the imperial throne. In the absence of a strong central authority, the empire broke into three competing states. The Roman provinces of Gaul, Britain, and Hispania broke off to form the Gallic Empire in 260. The eastern provinces of Syria, Palestine, and Aegyptus also became independent as the Palmyrene Empire in 267. The remaining provinces, centered on Italy, stayed under a single ruler but now faced threats on every side. An invasion of Macedonia and Greece by Goths, who had been displaced from their lands on the Black Sea, was defeated by emperor Claudius II Gothicus at the Battle of Naissus in 268 or 269. Historians see this victory as the turning point of the crisis. In its aftermath, a series of tough, energetic barracks emperors were able to reassert central authority. Further victories by Claudius Gothicus drove back the Alamanni and recovered Hispania from the Gallic Empire. He died of the plague in 270 and was succeeded by Aurelian, who had commanded the cavalry at Naissus. Aurelian reigned (270–275) through the worst of the crisis, gradually restoring the empire. He defeated the Vandals, Visigoths, Palmyrene Empire, and finally the remainder of