The text of the Athenian Dexippus has survived only indirectly through quotations in the fourth-century Augustan History. Modern historian David S. Potter declared this source to be poor despite its importance for the period. Surviving accounts include Zosimus' New History and George Syncellus' Selection of Chronography. These works rely principally on the lost history of Dexippus. The narrative provides an almost radically different interpretation of events compared to other sources. Imperial propaganda from Constantine's dynasty added more confusion by attributing all calamities to Gallienus. This was done to avoid blemishing the memory of Claudius who was a supposed ancestor of the dynasty. Controversy still exists regarding the number of invasions and the order of events. Scholars debate whether these events belong to the reign of Gallienus or Claudius II.
Two Maritime Invasions
A massive invasion began during the reign of Gallienus in 267 when Heruli raiders appeared on 500 ships. They ravaged the southern Black Sea coast and unsuccessfully attacked Byzantium and Cyzicus. The Roman navy defeated them but they escaped into the Aegean Sea. They sacked cities including Athens, Corinth, Argos, and Sparta. An Athenian militia led by the historian Dexippus pushed the invaders northward. The Roman army under Gallienus intercepted them near the Nestos River. Reported barbarian casualties reached 3,000 men before Heruli leader Naulobatus made terms with Romans. A second larger sea-borne invasion started later involving Goths, Gepids, and Peucini. Sources claim a total of 2,000 to 6,000 ships carrying 325,000 men though this is likely an exaggeration. The coalition assembled at the mouth of river Tyras and attacked towns like Tomis and Marcianopolis. Their fleet was wrecked while trying to sail through violent currents of the Propontis. They entered the Aegean Sea and ravaged islands as far as Crete and Rhodes.Imperial Military Maneuvers
Gallienus left Lucius Aurelius Marcianus in place after his victory near the Nestos River. He hastily left for Italy intending to suppress the revolt of cavalry officer Aureolus. Gallienus was assassinated outside Milan in the summer of 268 in a plot led by high officers. Claudius was proclaimed emperor and headed to Rome to establish his rule. His immediate concerns were with Alemanni who had invaded Raetia and Italy. He defeated them in the Battle of Lake Benacus before taking care of invasions in Balkan provinces. Aurelian was in charge of all Roman cavalry during the reign of Claudius. He led the decisive attack in the battle against the Goths. The Romans tricked the Goths into an ambush by pretending flight at the critical point. Large numbers on both sides were killed but the Romans ultimately prevailed.