Operation Ivy was an American ska punk band that formed in Berkeley, California, and was often credited with spurring the 1990s punk revival in California. It is well-known as one of the first bands to "mix" hardcore punk with elements of ska, known as ska-core. The band consisted of Jesse Michaels (lead vocals), Tim Armstrong (credited as "Lint") (guitar, vocals), Matt Freeman (credited as "Matt McCall") (bass, vocals), and Dave Mello (drums). Although Operation Ivy had little mainstream success during its career, the band had a large underground following and influenced bands such as Sublime and Green Day. Its only studio album, Energy, has been cited as one of the greatest punk rock albums of all time. The band's name, previously used by the punk band, Isocracy, was derived from the Operation Ivy series of nuclear tests.