 According to Plutarch, Arimnestus killed him by a blow to the head with a stone, a form of death which had been foretold to Mardonius by an oracle; some modern historians have called it unlikely that a Spartan would use such a weapon.With Mardonius dead, the Persians began to flee; although his bodyguard remained, they were annihilated.Herodotus claims that the reason for their discomfort was a lack of armour.