Black Flag’s My War completely altered the course of heavy music. Famously arriving after a multi-year legal battle, My War slowed their pioneering bursts of hardcore electricity down to trudging, ascetic crawls. Clamorous guitar dissonance, skull-numbing chugs and Henry Rollins’ worryingly self-interrogating lyrical barbs — screamed like a wounded animal, not a punk singer — were not what Flag fans necessarily wanted, but this still-contentious LP showed that hardcore could be heavy, and in turn provided a blueprint for the incoming wave of sludge-metal.