Taking control of the world and becoming the primary divinities was not so easy for Dias (Zeus) and his siblings. After his mother Rea saved him and helped him to free his other brothers and sisters, Zeus waged a war against the ruling Titans, his father Kronos', siblings to obtain power. For ten years the Olympian gods (from Mount Olympus) fought the Titans from Mount Orthys. Of the Titans, Hyperion, Iapetos, Koios, Krios, Kronos, Azeios, Atlas, Menoitios, Pallas, Perses and perhaps others that are not mentioned in some accounts, where all against the Olympians, while Helios assisted Zeus and Okeanos with the Titanides (the Titan girls: Themis, Theia, Rhea, Mnemosini, Phoebe and Tithis) all remained neutral.
After ten years of endless war, Gaia (the Earth) advised Zeus to free her sons, the Cyclops (3 one-eyed giants) and the Ekatonheires (3 creatures with 50 heads and 100 arms each) from the depths of the earth and seek their assistance in the war.
Read the rest here: allthegreeks.com
Source: www.theoi.com
Image: http://hellenicmythology.blogspot.com/2009/02/blog-post_27.html