Naval Inaction 259 CE

In the third century the Roman Empire was heavily beset by seaborne raiders. From c 251 to 270 CE, Goths and others launched a series of major assaults. The barbarians targeted the Danubian provinces of Moesia and Thrace, Greece, Asia Minor and islands in the eastern Mediterranean.

Aware of the possibility of attacks by sea, the Romans established four fleets to deal with them. One, the Classis Pontica, patrolled the southern Black Sea. Another, the Classis Moesica, defended the western part. If they failed to halt a thrust into the Mediterranean, the Classis Syriaca and Classis Alexandrina formed a reserve.

Against the early incursions, the Roman navy performed well. Despite attacks in Anatolia and Greece in 251 and 253, the Classis Syriaca beat the enemy near Rhodes, Crete and Cyprus. Another raid on Anatolia in 254 was similarly beaten. In 256, Gallienus, co-emperor in the West (while Emperor Valerian was in Syria) launched counterattacks along the Rhine and Danube.

In 259, however, a massive raid seems to have gone unopposed. Passing down the lower Danube in boats, the Goths first looted Moesia and Thrace, then reached the Propontis. With several hundred vessels they surrounded and overran Cyzicus, in the process neutralizing the Classis Pontica. Proceeding southward, the marauders then plundered Athens, the Pelopponese, the Ionian coast and the temple of Ephesus.

On this occasion the Roman fleet was conspicuous by its absence. Where was the Classis Syriaca, which had distinguished itself a few years earlier? No doubt Roman historians would've mentioned any success in 259, just as they recorded victories before and after that date.

The problem was the increased threat of invasion by land. In those circumstances, the navy lost men to the army. With regard to the eastern fleets, the specific problem was Persia.

By 259 the Romans were bracing themselves for a major Sassanian attack. The Persian king, Shapur, was eager to plunder Rome's eastern provinces. The Persians had already captured Dura Europos c 256, and in 258 Valerian, seeking the support of Odainathus, the Palmyrene ruler, made him vir consularis. The emperor must have known the Persians were coming, well before their invasion materialized in 260 CE.

Considering the importance of Syria and Egypt to the Empire, Valerian was determined to protect them. If Syria were overrun, Egypt might go too, costing Rome most of its grain supply. So it is likely Valerian, by 259, ordered maximimum emphasis on the army, even if it meant sacrificing the eastern fleets. The soldiers manning ships were to be added to the legions guarding Syria.

Valerian and his generals were aware of the risk they were taking. In order to focus on Persia,  they left the Balkans and Asia Minor to their fate. Experience had shown that the Classis Pontica (even if intact) was not sufficient to prevent Gothic penetration of the Aegean and beyond. After Successionus, a Roman officer, won a victory against the Goths, Valerian promoted him. But the emperor seemed unable or unwilling to stop the sea assaults of 259.

Valerian's gamble failed miserably. His sacrifice of Athens, and Ephesus etc did not prevent the smashing defeat of his army by Shapur, or the sacking of Syria.

Fortunately for the Balkans and Asia Minor, Persia soon ceased to drain resources from the fleet. After 260, Sassanid power greatly ebbed. Odainathus's march on Ctesiphon in 262 attested to this. Apparently learning the lesson of 259, the Romans under Gallienus revived the eastern fleets.

In 268, with a rebuilt Classis Pontica, Venetianus demolished a Gothic fleet, and while its remnants sacked Athens, they were soon wiped out.

In 269 the Romans won the greatest naval victory of the Imperial era. Commanding the Classis Syriaca, Probus annihilated a Gothic armada. After destroying the barbarian warships the Romans captured those carrying civilians and baggage. The enemy, who first attacked Rhodes, Crete and Cyprus, failed utterly against Roman reserves, including the Classis Alexandrina, which assisted the Classis Syriaca.

Probus's victory was decisive. For over a century, there were no further Gothic sea raids. The barbarians simply could not match Roman naval power, and their expeditions, while lucrative, ultimately proved too costly.

A Roman warship battling Gothic raiders

Reference

Raffaele D'Amato Imperial Roman Warships 193--565 AD  Osprey Publishing 2017