Ancient stele in Istanbul Archaeology Museum: Athena to the left is attacking two giants who try to flee, which is a bit difficult with their serpent's legs. Both wear lion pelts, the one to the right tries to protect himself with it. Roman, 2nd century BC from Aphrodisias.
Gigantomachy was the symbolic struggle between the cosmic order of the Olympians led by Zeus and the nether forces of Chaos led by the giant Alcyoneus in Greek mythology. Heracles fought on the side of Olympians, who defeated the Giants in accordance with Hera's prophecy that the gods' victory would not be accomplished without the participation of the son of a mortal mother.
After the Titanomachy, the goddess Gaia, seeking revenge, brought forth the Giants, telling them to "take arms against the great gods". Hesiod describes them as "glittering in their armour, with long spears in their hands."
The Gigantomachy became a popular theme from the early 7th century BC. A temple at Phanagoreia commemorated Aphrodite's victory over some Giants. She drove them into a cave, where Heracles slaughtered them. After the Greco-Persian Wars the representation of Gigantomachy symbolized the hostility between the Greeks and the Persians, with the Greeks figuring as the Olympians, and the Persians as Giants.
Following the fashions, originally developed in Hellenistic Alexandria, for rationalized glosses on the archaic myths and for allegorical interpretations, the fifth-century court poet of Honorius, Claudian, composed a Gigantomachia, that viewed Gigantomachy as a metaphor for catastrophic geomorphic change: "The puissant company of the giants confounds all differences between things; islands abandon the deep; mountains lie hidden in the sea. Many a river is left dry or has altered its ancient course....robbed of her mountains Earth sank into level plains, parted among her own sons."