The singer Ozzy Osbourne helped to form Black Sabbath in the 60s alongside Tony Iommi, Geezer Butler and Bill Ward. They quickly changed the course of Rock and Roll with the release of their first albums in the early 70s, creating what later would be called Heavy Metal. Their success continued during that decade but the heavy use of drugs made the band decide to fire Ozzy and then they invited the ex-Rainbow vocalist Ronnie James Dio to join them. The first album of that new line-up was "Heaven & Hell", which became a really praised record. But during those first years in the band, Dio had to perform many tracks which were originally recorded with Osbourne, since those were the fans favorite tracks. Although he obviously preferred the track he helped to write and record, he also loved some songs from the Ozzy era and he once revealed which was one of his favorites. The Black Sabbath song with Ozzy that Ronnie James Dio liked It was in an interview with Rhapsody Blog back in 2009 that Ronnie James Dio listed some of his favorite songs of all time. One of the tracks he chose was "War Pigs", originally released by Black Sabbath on their second album "Paranoid" (1970). “It was another one of those songs where you didn’t expect it to go where it went. I just thought it was so well written and so well performed. So different, so unusual. It’s one of the standard-bearing songs for the band. I think it will always be remembered within the same confines as ‘Paranoid’, ‘Iron Man’ and ‘War Pigs’. They just seem to go together." Dio continued: https://www.youtube.com/watch?v=tN3kQ9E2WP8&pp=ygUMZGlvIHdhciBwaWdz "That was Geezer’s lyrics. They stand up because that was a protest about people who were creating war. They’ve never heard that before. That’s a strange title, isn’t it? You just put that together and it’s so clever. Musically, it was just written so well. That’s my 10,” Ronnie James Dio said. As Dio said, "War Pigs" became one of Black Sabbath's signature songs. It had been frequently featured on their setlists since it was released in 1970. As Sabbath's guitarist Tony Iommi said many times, the main difference between Ozzy and Dio was that the American singer used to sing even when the riffs of the songs were being played. Ozzy usually didn't do that and there was silence in the vocals when Iommi was playing the riffs. Dio was a member of Black Sabbath from 1979 to 1982, recording two studio albums: "Heaven and Hell" (1980) and "Mob Rules" (1981). He then returned from 1991 to 1992, recording "Dehumanizer" (1992). Also returning from 2006 to 2010, when the band was renamed "Heaven and Hell", releasing "The Devil You Know" (2009).