What is Hera's plan? Books 11-15

Hera devises a plan to seduce Zeus, luring him back from Ida so that he cannot help the Trojans. She dupes Aphrodite into helping her, saying that she needs a token to bring together two estranged lovers. Aphrodite gives her a band, worn between the breasts, that makes its wearer irresistible. Hera then goes to the god Sleep, asking him to put Zeus to sleep once Hera has lain with him. Sleep is afraid, because on one other occasion he put Zeus to sleep so that Hera could work mischief. On that day, Sleep only escaped because of the protection of Night, a goddess that even Zeus fears to anger. But Hera offers Sleep one of the Graces as a bride, and Sleep agrees to help her.

On Ida, Hera approaches Zeus, who is overcome by passion. The two deities sleep together, and Sleep goes to Poseidon to tell him that Zeus slumbers and can no longer stop him from helping the Greeks.