Following his departure from Rainbow in 1979, Dio joined Black Sabbath, replacing the fired Ozzy Osbourne. Dio met Sabbath guitarist Tony Iommi by chance at The Rainbow on Sunset Strip in Los Angeles in 1979. Both men were in similar situations, as Dio was seeking a new project and Iommi needed a vocalist. Dio said of the encounter, "It must have been fate, because we connected so instantly." The pair kept in touch until Dio arrived at Iommi's Los Angeles house for a relaxed, getting-to-know-you jam session. On that first day the duo wrote the song, "Children of the Sea", which appeared on the "Heaven and Hell" album, the first the band recorded with Dio as vocalist, released in 1980.