Through a combination of zealous righteousness and post-punk experimentalism, U2 became one of the most popular rock & roll bands of the '80s. They were rock & roll crusaders during an era of synthesized pop and heavy metal, equally known for their sweeping sound as for their grandiose statements about politics and religion. The Edge provided the group with a signature sound by creating sweeping sonic landscapes with his heavily processed, echoed guitars. Though the Edge's style wasn't conventional, the rhythm section of Larry Mullen, Jr. and Adam Clayton played the songs as driving hard rock, giving the band a forceful, powerful edge that was designed for arenas. And their lead singer, Bono, was a frontman with a knack of grand gestures that played better in stadiums than small clubs. It's no accident that footage of Bono parading with a white flag with "Sunday Bloody Sunday" blaring in the background became the defining moment of U2's early career -- there rarely was a band that believed so deeply in rock's potential for revolution as U2, and there rarely was a band whose members didn't care if they appeared foolish in the process.