Birth Control's second album, Operation (1971), defined the band's sound and propelled them to success throughout Central Europe. The album showcased the band's skillful execution of heavy prog, with ominous organ breaks, hard guitars, and complex progressive passages. The provocative album cover, featuring a cockroach feasting on helpless infants, caused controversy and increased the band's press coverage and vinyl sales. Birth Control's early 70s releases paved the way for their later symphonic prog sound, and they will always be remembered for their strong, daring, and provocative releases.