How did rhea prevent cronos from swallowing Zeus?

Rhea prevented Cronos from swallowing Zeus by secretly giving birth to him in a cave on Mount Ida and then wrapping a stone in swaddling clothes, which Cronos swallowed instead, believing it to be his newborn son. Rhea then hid Zeus and raised him away from Cronos, allowing him to grow strong enough to challenge his father. Eventually, Zeus would return to confront Cronos, leading to the Titanomachy and the overthrow of the Titans.