By the 880s the eastern Mediterranean had tilted against the Byzantines. Two losses in the previous century had done it: the slow Muslim conquest of Sicily and, more dangerously, the establishment of the Emirate of Crete. With Crete in Arab hands, the Aegean lay open to raiders who could strike almost anywhere along the Greek coast and slip away before help arrived. The Abbasid caliphs reinforced their frontier bases as well, and the Cilician city of Tarsos became a launching point for fleets and armies aimed at Byzantine territory. Its governor from 882 to 891 was a man named Yazaman al-Khadim, an aggressive commander who turned raiding into a near-annual habit.

In 883 Yazaman beat off a major Byzantine attack, and the following year he gathered his strength for a raid deep into Greece. His target was Euripos, the Byzantine name for Chalcis, a city straddling the narrow Euripus Strait where the island of Euboea nearly touches the mainland. It is one of the strangest stretches of water in the Mediterranean; the current through the strait reverses direction several times a day, baffling sailors since antiquity. According to the chronicler John Skylitzes, Yazaman sailed with thirty koumbaria, heavy warships built for both battle and cargo. But word of his plans had already reached Constantinople, and Emperor Basil I had time to prepare a defense.

The governor of the Theme of Hellas, a man Skylitzes calls Oineiates, used that warning well. He gathered the troops of his province, repaired the city walls, and mounted stone-throwing catapults along them. When Yazaman's ships came, the defenders met them with everything they had. Skylitzes describes the attackers being driven back "with their machines for hurling stones, missiles and darts, to say nothing of stones thrown from the walls by hand." Out on the water, Byzantine ships armed with Greek fire, the empire's terrifying incendiary weapon, darted among the Arab vessels and sent several of them to the bottom. Wave after wave of assault broke against the city, and the strait filled with wreckage.

When force alone would not crack the walls, Yazaman tried greed. He placed the gold-laden shield before his troops and made his promise to the first man over the top. It was a calculated gamble, meant to buy with treasure what his soldiers could not take by storm. But the defenders read it correctly. Seeing the offering, they knew the decisive attack was at hand, and rather than wait for it they steadied each other with shouts and burst out of the gates in a sortie of their own. The sudden charge caught the besiegers off balance. Many of Yazaman's men were killed; the rest broke and fled to their ships. The raid that was meant to plunder Chalcis ended as a rout on its shore.

Skylitzes claims Yazaman himself fell in the fighting, but that is a slip; Arab sources record him raiding Byzantium again in 886 and 888 before he died in 891, besieging a different fortress. The victory at Euripos was real but local. Arab raids on Greek waters continued and grew worse, reaching a horrifying peak in 904 when Leo of Tripoli sacked Thessalonica, the empire's second city, and carried thousands into slavery. Only after the 920s did the balance finally swing back, ending with the Byzantine recovery of Crete and Cilicia decades later. For one season, though, the people of a city on the churning strait had held, and turned an enemy's gold against him.