Titanomachy and Gigantomachy

What happened immediately after [Kronos regurgitated his children] is not clear, but the war between the gods and Titans - the Titanomachy - soon begins. Unfortunately the epic poem of that name, which would have told us much, is lost. The first complete account we have is in Apollodorus (which was probably written in the 1st century A.D.).

Some of the children of the other Titans - such as Iapetos' son Menoetius - fought alongside their forebears. Others - including Iapetos' other children Prometheus and Epimetheus - did not.

The war was fought without success on either side for ten years (a traditional period for a long war; note that the Trojan War also lasted ten years), with the gods based on Mount Olympus, and the Titans on Mount Othrys. These two mountains flank the area of northern Greece called Thessaly, Olympus to the north, and Othrys to the south.

Since both sides of this war were immortal, no permanent casualties were possible. Finally, however, the gods triumphed with the aid of older powers.

Ouranos had long ago imprisoned the three Cyclopes and the three Hundred-Handers (Hekatoncheires) in dark Tartaros. Again advised by Gaia, Zeus freed these monstrous cousins of the Titans and was rewarded with their aid. The Cyclopes gave lightning and thunder to Zeus to wield as weapons, and in later accounts also created Hades' helmet of darkness and Poseidon's trident.

The Hundred-Handers provided more direct assistance. In the final battle, they kept the Titans under a constant barrage of hundreds of thrown rocks, which together with the other gods' strengths, particularly Zeus' thunderbolts, overcame the Titans. The defeated Titans were hauled down to Tartaros and imprisoned there, and the Hundred-Handers became their jailors.

Or at least that is how Hesiod concludes his vivid description of the battle. However, elsewhere in his Theogony, and in other poems, we see that in fact many of the Titans did not remain there.

The children of Iapetos had varied fates - Menoetius was like his father cast into Tartaros, or destroyed by Zeus' thunderbolt. But the varied fates of Iapetos' other sons - Atlas, Prometheus, and Epimetheus - did not involve imprisonment for fighting in the war.

Many of the female Titans or daughters of the Titans - such as Themis, Mnemosyne, Metis - were also obviously not imprisoned. (Perhaps they did not participate in the fighting.) In any case, they became the mothers of the Muses, Horai, Moirai, and - in a manner of speaking - Athena.

The mythological record is silent on most of the rest of the Titans, but a later myth said that Kronos himself was eventually released by Zeus, and he was assigned to rule over the Isles of the Blessed, where the spirits of heroes went after death. Source

Definition of Gigantomachy:

Duplication abounds in Greek mythology. The story of the Gigantomachy, a sequel to the similar Titanomachy, is an excellent example.

After the Titanomachy, where Zeus defeats the Titans and places them in Tartarus, an angry Gaia brings forth the giants (gigantes) to restore the rule of the Titans. These giants are not simply big, but have multiple hands and snake legs. Pindar mentions the theft of the cattle of the sun god Helios, as initiating combat. Another version makes the precipitating factor the rape of Hera by a giant named Eurymedon (or Porphyrion). The gods, led by Zeus -- now more powerful than in the Titanomachy because he has thunderbolts, fight against immortal giants, led by Alcyoneus the cattle-thief and Porphyrion. The result is inevitable: Zeus wins, but only with help from Hercules / Heracles, Alcyoneus's killer. Alcyoneus is only immortal as long as he is in his place of birth, so Hercules removes him from Phlegra. Hercules does this elsewhere in Greek mythology when he lifts the Libyan giant Antaeus to remove him from the source of his strength, his mother, Gaia.

Another duplication in the Gigantomachy is the prophesied need for 2 demigods to defeat the giants. The second son of Zeus is Dionysus, who, accompanied by satyrs and silenoi, kills Ephialtes with his thyrsos. After the rest of the giants are killed by the gods, Hercules shoots them with his bow -- just to make sure they really are finished.

After their defeat, and in contrast with the version of them being killed, the giants are placed beneath the Earth where they continue to make mischief by causing volcanoes and earthquakes.

Sources:
Carlos Parada, Timothy Gantz, and The Titans and Early Greek Mythology

Ancient Sources on the Giants include: Apollodorus, Apollonius of Rhodes, Bacchylides, Diodorus Siculus, Euripides, Hesiod, Homer, Ibycus, Ovid, Pausanias, Pindar, Sophocles, and Strabo.

Also Known As: Battle of the Giants.

Phlegraean fight:
The Phlegraean fields are either in Italy (Campania, Strabo and possibly Pindar) or the Thracian Isthmus of Pallene(Oskar Seyffert (1894) A Dictionary of Classical Antiquities).

Examples:
Eumenes II Soter (197-160/59) commissioned a giant frieze of the chaotic events of the Gigantomachy. The relief was 7' high and more than 400' long in Pergamum on the altar of Zeus and Athena. It shows more than 1200 divinities and other mythological figures.

Source