…lays siege to the island of Chios.
Philip is planning to use the northern Aegean islands as stepping stones as he works his way down to Rhodes.
The siege is not going well for Philip, as the combined fleets of Pergamon, Rhodes and their new allies, Cyzicus and Byzantium, have successfully blockaded his fleet.
Philip, seeing no other option, decides to risk battle against the allies.
The Macedonian fleet of around two hundred ships outnumbers the allied fleet around two to one.
The battle begins with Attalus, who is commanding the allied left wing, advancing against the Macedonian right wing, while the allied right flank under the command of the Rhodian admiral, Theophiliscus attacks the Macedonian's left wing.
The allies gain the upper hand on their left flank and capture Philip's flagship; Philip's admiral, Democrates, is slain in the fighting.
Meanwhile, on the allied right flank, the Macedonians are pushing the Rhodians back.
Theophiliscus, fighting on his flagship, receives three fatal wounds but manages to rally his men and defeat the Macedonian boarders.
On the allied left flank, Attalus sees one of his ships being sunk by the enemy and the one next to it in danger.
He decides to sail to the rescue with two quadriremes and his flagship.
Philip, however, whose ship has not been involved in the fighting to this point, sees that Attalus has strayed some distance from his fleet and sails to attack him with four quinqueremes and three hemioliae.
Attalus, seeing Philip approaching, flees in terror and is forced to run his ships aground.
Upon landing he spreads coins, purple robes and other splendid articles on the deck of his ship and flees to the city of Erythrae.
When the Macedonians arrive at the shore, they stop to collect the plunder.
Philip, thinking that Attalus has perished in the chase, starts towing away the Pergamese flagship.
The situation on the allies' right flank, meanwhile, has reversed and the Macedonians are forced to disengage and retreat, leaving the Rhodians to tow their damaged ships into the harbor at Chios.
The allied left and center have also gained the advantage earlier and forced the Macedonians to retreat before sailing back to Chios unmolested.
The battle is a costly one for Philip, who has lost ninety-two ships destroyed and seven captured.
On the allied side, the Pergamese have had three ships destroyed and two captured, while the Rhodians have lost three ships sunk and none captured.
During the battle the Macedonians had lost six thousand rowers and three thousand marines killed and had two thousand men captured.
The casualties for the allies are significantly lower, with the Pergamese losing seventy men the Rhodians sixty killed, the allies as a whole losing six hundred captured.
Peter Green, in Alexander to Actium: The Historical Evolution of the Hellenistic Age, describes this action as "a crippling and costly defeat".
This defeat effectively cripples the Macedonian fleet and saves the Aegean islands from another large invasion.
After this battle, the Rhodian admirals decide to leave Chios and sail back home.
