After a 10-year hiatus, the Goths and the Heruli, with a raiding fleet of 500 ships, sacked Heraclea Pontica, Cyzicus and Byzantium. They were defeated by the Roman navy but managed to escape into the Aegean Sea, where they ravaged the islands of Lemnos and Scyros, broke through Thermopylae and sacked several cities of southern Greece (province of Achaea) including Athens, Corinth, Argos, Olympia and Sparta. Then an Athenian militia, led by the historian Dexippus, pushed the invaders to the north where they were intercepted by the Roman army under Gallienus. He won an important victory near the Nessos (Nestos) river, on the boundary between Macedonia and Thrace, the Dalmatian cavalry of the Roman army earning a reputation as good fighters. Reported barbarian casualties were 3,000 men. Subsequently, the Heruli leader Naulobatus came to terms with the Romans.