He was able to win over every city on the island except for the Graeco-Phoenician city-state of Amathus, which stayed loyal to the Persians despite being besieged by Onesilus' troops.
As a result, the Ionian fleet retreated from Cyprus and five months later the Persians regained control of the island.
Herodotus also reports that in retaliation for Onesilus' siege of Amathus, the townspeople cut off his head after his death and hung it above the town gates as a trophy, and later observed that his desiccated skull had been occupied by a swarm of bees and their honeycomb (a phenomenon similar to bugonia).
To ward off the effects of this ill omen they were advised to take down the head and bury it, making sacrifice to Onesilus as a hero.
[1] The story of the bees in the skull is the subject of "histories: onesilos", a poem by German poet Jan Wagner.