On Olympus the gods looked down on the Greek mound and wall.  Poseidon was irritated because the proper offerings had not been made before the building began.

Zeus calmed Poseidon saying that a lesser god might be offended but he, the great and powerful god of the sea, could wash away the wall and mound after the Greeks set sail for home.

Zeus the profound made thunder all night.  The men, pale with fear, spilled wine on the ground as offerings.  Eventually they turned to rest and fell asleep.