The battle of Chios of 201 B.C. was the first of two naval battles fought by Philip V of Macedonia off the coast of Asia Minor during 201. In 202 Philip had begun a campaign of conquest in the Aegean, attacking independent Greek cities. This had worried Rhodes and Attalus of Pergamum so much that they had gone to war with Philip.
The battle of Chios happened while Philip was attacking either Chios or Pergamum. The army was supported by a fleet contained 53 cataphracts and 150 lembi (light ships popular in Illyria).
Attalus and the Rhodians decided to attack Philip off Chios. Their combined fleet contained 65 cataphracts, 3 light trieres and 9 even lighter triemioli.
The two fleets met in the south of the Chian channel. The battle seems to have fallen into two halves, with the allied fleets attacking different parts of the Macedonian fleet. Attalus fought Philip near the coast of Asia Minor, while the Macedonian rear fought the Rhodians near the island of Chios.
Both parts of the battle seemed to be going against Philip, but then Attalus attempted to prevent one of his ships from being sunk, and was driven onto the shore. Philip captured Attalus’s ship, and towed it back through the battle, convincing the rest of the Pergamene fleet that the king was dead. The Pergamene fleets then withdrew. The Macedonians took advantage of this lull to escape from the victorious Rhodians.
Philip suffered the heaviest losses during the battle, losing 28 cataphracts and 65-72 of the lembi. Attalus lost three ships sunk and one captured, the Rhodians lost three sunk. Polybius claimed that Philip lost 12,000 men, the allies only 130 (although one of them was the Rhodian admiral Theophiliscus, who died of his wounds after the battle), and that on the day after the battle Philip refused to fight when the combined Allied fleet offered battle.
Whatever the truth of that in the aftermath of the battle the allied fleet was broken up. Philip inflicted a minor defeat on the Rhodian fleet at Lade, further south along the coast, but the losses suffered at Chios meant that Philip’s fleet didn’t play a major role in the Second Macedonian War.