The backstory begins three decades earlier, when the Byzantine Empire lost control of two islands that had anchored its Mediterranean supremacy. In the 820s, Arab forces began the conquest of Sicily, and Andalusian exiles seized Crete, establishing an emirate that turned the island into a haven for Muslim fleets and a base for raids across the Aegean Sea. The Byzantines tried and failed to retake Crete -- a large-scale invasion in 842 or 843 ended in heavy losses. Arab pirates raided the Christian shores of southern Europe almost at will, penetrating as far as Italy and the Adriatic. By mid-century, Constantinople needed a new strategy. Rather than throw another fleet at Crete's fortified harbors, the Byzantine government decided to cut the emirate's supply lines. Egypt, which historian Alexander Vasiliev called "the arsenal of the Cretan pirates," was the obvious target.

According to the Arab historian al-Tabari, the Byzantines assembled nearly three hundred ships and dispatched them on simultaneous raids against Muslim naval bases across the eastern Mediterranean. The precise targets of two of the fleets remain unknown. The third -- eighty-five ships carrying five thousand men under a commander Arab sources identify only as "Ibn Qatuna" -- sailed for Egypt. Modern scholars have proposed various identifications for this mysterious commander, from the parakoimomenos Damian to the strategos Photeinos, but none can be confirmed. What is certain is that Egyptian defenses were in no condition to resist. The Egyptian fleet had withered since its Umayyad-era peak and was deployed mainly on the Nile, not in the open Mediterranean. Coastal fortifications, once manned by volunteer garrisons, had been abandoned decades earlier. The Byzantines had already exploited this weakness with smaller raids in 811 and 812. Damietta in 853 was the culmination.

After sacking Damietta over two days, the Byzantine fleet sailed east and attacked the fortress of Ushtum, burning the siege engines and artillery stored there before withdrawing. The raid's military impact was immediate: the Byzantines returned to strike Damietta again in 854, and possibly a third time in 855. In 859 they attacked Farama. Yet the deeper consequence was not what the Byzantines destroyed but what Egypt rebuilt. Governor Anbasah, stung by the humiliation, launched an urgent refortification of the coast. Within nine months, Damietta, Tinnis, and Alexandria were strengthened, and works were undertaken at Rosetta, Borollos, and several other ports. New ships were constructed and crews raised -- many of them forcibly conscripted from among the Copts and the Arabs of the interior, a policy that earned Anbasah bitter complaints to Caliph al-Mutawakkil.

Ironically, the raid that humiliated Egypt catalyzed the revival of its naval power. The fleet that Anbasah built was the foundation on which later dynasties would construct a Mediterranean force to rival the Byzantines themselves. Under the Tulunid dynasty, which ruled Egypt from 868 to 905, the navy grew to a hundred ships. Under the Fatimids, who took Egypt in 969, it reached its peak and became one of the most formidable fleets in the medieval Mediterranean. Meanwhile, the Byzantine strategy of severing Crete's supply lines ultimately failed to stop Aegean piracy, which intensified through the early 900s. The sack of Thessalonica -- the empire's second city -- by Arab raiders in 904 marked the nadir. It would take until 961 for Constantinople to finally reconquer Crete. The 853 raid on Damietta achieved a tactical triumph but triggered a strategic transformation that worked against Byzantine interests for generations.