What did the titans do that they were banished to tartarus?

Answer 1

Cronus, the most powerful Titan of all, had heard of a prophecy that his son would overthrow him. He then began to eat his children (the 5 original Gods/Goddesses besides Zeus) in order to prevent this from happening. His wife, Rhea, when Zeus was born, had sent him away and put a boulder in his place so Cronus wouldn't get suspicious of his disappearance. Then, when Zeus became powerful enough, he had mastered all elements that the monsters wielded, and had freed his siblings, and engaged in all-out war. In the end, the Immortals had won and had punished the Titans individually (Atlas had to hold the sky from crushing the Earth, etc).