Titanomachy

After Zeus saved his siblings, he decided to wage war against the Titans.
Zeus had on his side his siblings Hades and Poseidon.
The Cyclopes and Hekantochires also joined Zeus side after he had rescued them, but also the Titan Prometheus with his mother Clymene sided with Zeus.
They were based on mount Olympus

On the other side, the Titans  that took part in the war were
Hyperion, Coeus, Cronus,Crius and Iapetus.
Iapetus sons  Menoetius and Atlas took also part in the war.
Atlas was an important leader for the titans during the Titanomachy.
They were based on  Mount Othrys.

Some of the titans and their children choose not take part in the war, they preferred to wait and see what side would be victorious.

Initially when the war started Zeus had on his side only his 2 brothers and for many years the both the Olympian gods and the Titans were equally strong but when eventually the cyclopes, the Hekantochires and Prometheus
joined Zeus side and victory came closer for the Olympians.

The cyclopes were very skilled in creating new useful weapons for the gods and the Hekantochires used their hundreds of hands to throw rocks and mountains to the titans causing them great damage.

During the war the earth was shaking, the sea was boiling and the sky creaked and groaned. After ten years of war the Titans had become weak and could barely fight anymore. So Zeus launched a final attack using his lightening bolts and one such bolt struck Menoetius, sending him into the depths of Tartarus.

This was the end of the war and victory for the Olympian gods.

After the war Zeus punished all the titans that opposed him by sending them to Tartarus to be imprisoned by new bronze gates crafted by Poseidon and the Cyclopes. The Hecatonchires were given the position of prison guards.
 Atlas was given special punishment though, for he was charged with holding up the damaged sky for all eternity. The Cyclopes would become craftsmen for the gods with forges upon Mount Olympus and beneath various volcanoes.

The remaining Titans that did not take part in the war were not punished and remained free.
  
The cosmos was itself divided amongst the three male Olympians through the drawing of lots. So Hades was given dominion over the Underworld, Poseidon became lord of the world’s waters and Zeus became lord of the heavens, and with it the position of supreme deity.