In the ninth century, Crete was not a quiet Mediterranean island but the base of an Arab emirate that had made seaborne raiding into an organized campaign. The emirate had been founded by Abu Hafs, and by the early reign of Emperor Basil I the Macedonian, his son Shu'ayb was sending out large fleets against Byzantine coastal settlements. The raiders who struck the Aegean shores were not small parties of opportunists. The force Photios commanded comprised over fifty vessels, including twenty-seven heavy warships — the type the Byzantines called koumbaria — supported by lighter galleys. This was a military expedition of substantial scale, designed to strip the coastlines of valuables and people. The prisoners taken along the Aegean were to be sold as enslaved people, a fate that awaited those captured on coasts from the Adriatic to the Black Sea during this period. What made this particular expedition alarming was its ambition: Photios pushed through the Aegean, into the Sea of Marmara, reaching the island of Prokonnesos in the shadow of Constantinople itself.

The Byzantine droungarios of the Fleet — the senior naval commander — was Niketas Ooryphas. He intercepted the Cretan fleet in the waters off Kardia, where the ancient city of that name overlooked the Gulf of Saros at the northern end of the Gallipoli Peninsula. The weapon that decided the engagement was Greek fire, the incendiary compound that Byzantine warships deployed through projecting tubes — its exact formula is still debated by historians, but its effects in combat are not. Twenty Saracen vessels were destroyed. The rest fled south toward Crete. What had entered the Gulf of Saros as a threatening raider force departed as a routed remnant, carrying the news that the waters near Constantinople were defended.

Photios was not finished. Some time after his defeat off Kardia, he led a second expedition against Greece. Niketas Ooryphas caught up with him again. This encounter, possibly in the Gulf of Corinth, destroyed Photios's fleet completely and killed him. The sequence of two defeats — first at Kardia, then in Greek waters — effectively ended the particular threat this commander had posed. The chronicler Theophanes Continuatus recorded both campaigns in terms the later historian John Skylitzes repeated almost verbatim, which gives the Kardia battle a longer textual life than most ninth-century naval engagements. The precise year remains disputed: some scholars following Heinz Hunger place the battle at 872, while others including Warren Treadgold and John Pryor argue for a slightly different date within the same decade.

The Gulf of Saros opens northward from the Gallipoli Peninsula, a broad sweep of blue water bounded by low hills on three sides. The ancient city of Kardia once commanded its entrance from the western shore, a position that made it a natural choke point for naval traffic moving between the Aegean and the straits. That city is long gone, its ruins somewhere beneath the fields and shores near modern Bolayır. The naval battle fought in these waters in the ninth century left nothing visible in the landscape — no monument, no wreckage, only the names in the chronicles and the knowledge that somewhere in this bay, the trajectory of a Cretan fleet ended in smoke and Greek fire.