The First Mithridatic War had begun with what the Greeks called the Asian Vespers, a coordinated massacre of Romans and Italians across Asia Minor that may have killed eighty thousand civilians in a single day. The Roman governor Lucius Cassius escaped the slaughter and fled to Rhodes, the one island that had stayed loyal to Rome. Italian refugees followed him, swelling the defenders. When word reached Rhodes that Mithridates was sailing south after taking Kos and Lesbos, the city demolished every building outside the walls to deny cover to attackers. The defenders had perhaps a hundred ships and roughly five thousand fighters; Mithridates was bringing many times that, in personal command of his invasion fleet.

Mithridates's chief engineer had built him something rare: a sambuca-style assault tower mounted across two warships, with bridges that could be dropped onto a city wall directly from the sea. The device had been invented more than a century earlier by Heracleides of Tarentum for use against Syracuse, and it was the kind of weapon that worked on theory more often than on water. Mithridates anchored off Rhodes, deployed the contraption, and discovered what every naval engineer learns the hard way: a tower top-heavy enough to clear a city wall is also top-heavy enough to capsize when its own warships heave on a swell. The sambuca came apart. The assault stalled before it had begun.

The Rhodian admiral Demagoras was a careful man. His fleet was outnumbered perhaps three to one, and he had no intention of meeting the Pontic line in open water. He used what he had: the speed of Rhodian biremes, knowledge of the harbour approaches, and the willingness to wait. When a royal Pontic supply ship drifted too close to the port, a single bireme darted out, took the prize, and was back behind the mole before the Pontic fleet could react. Reinforcements rushed up; a melee followed in which the Rhodians, in the words of Appian, circled skilfully and rammed his ships to such effect that the battle ended with the Rhodians retiring into their harbour with a captured trireme in tow and other spoils besides. Mithridates lost a few more ships in a clumsy night pursuit, and his own flagship was rammed by accident by a vessel from his ally Chios. He noted the incident; the Chians would pay for it later.

Mithridates broke off the siege without a decisive battle on land. He had not lost catastrophically, but he had not taken the island, and Rhodes had shown what every later Roman commander would exploit: the king's coalition was wider than it was deep. Greek cities that had thrown open their gates to him discovered that liberation came with extraordinary taxes; allies discovered that the king trusted no one. Within four years a Roman general named Sulla had landed in Greece, retaken Athens, and forced Mithridates to a peace that returned everything he had conquered. Rhodes received the title Friend and Ally of Rome and kept the trading privileges that title carried. Demagoras, who had no statue and no surviving portrait, kept his reputation among Rhodians for the same reason every successful island commander does: he had read the weather, the ships, and the moment correctly.

Rhodes had been besieged before, and would be again, and would lose eventually. In 305 BC it had outlasted Demetrius the Besieger; in 1522 it would fall to Suleiman the Magnificent after six terrible months. The 88 BC siege sits between those two famous catastrophes as a quieter kind of victory, the sort that does not produce a Colossus or a Davenant opera but does keep a small republic alive for another generation. The lesson the Rhodians repeated, century after century, was that a navy does not have to win in line of battle. It only has to make the losses unbearable for the side that came to take the harbour. By that measure Demagoras's biremes did exactly what they were built to do.