Complex sentence: During the war against the Titans, Tethys raised and educated Hera as her step-child, who was brought to her by Rhea... the time when Zeus caused Father Kronos to sink beneath the earth and sea.
Split into simpler sentences: During the war against the Titans, Tethys raised and educated Hera as her step-child. Hera was brought to Tethys by Rhea... the time when Zeus caused Father Kronos to sink beneath the earth and sea.