Complex sentence: For the Greeks, the Gigantomachy represented a victory for order over chaos--the victory of the divine order and rationalism of the Olympian gods over the discord and excessive violence of the earth-born chthonic Giants.
Split into simpler sentences: For the Greeks, the Gigantomachy represented a victory for order over chaos. The victory of the divine order and rationalism of the Olympian gods over the discord and excessive violence of the earth-born chthonic Giants.