Dorieus was a half-brother to King Cleomenes I and a brother of Leonidas, who later became king and famous as the Spartan commander at the Battle of Thermopylae.
Learning of Dorieus's plight, Mindarus hurried from Troy, where he had been sacrificing to Athena, to Abydos, while Pharnabazus brought his army up to support Dorieus from the land.