This one is probably the greatest opening track to any album in the history of music. It sets the stage for the urgent feel of the rest of the album, and creates a sense of paranoia that can still be felt today....especially today, actually. This song is a call-to-arms for everyone, warning of a coming apocalypse fueled by the then-current fear of nuclear annihilation. The instrumentation fits Joe Strummer's vocals perfectly, with it's muscular bass line and the greatest punk guitar riff ever recorded. For the 3:20 seconds of this song, The Clash are the greatest band of all time.