This 1966 landmark album, along with the debut Butterfield Blues Band record that shipped the previous year, launched the blues-rock revolution of the mid-'60s. Eric Clapton, who'd skipped out on the Yardbirds to explore his deep-blues muse, was given every opportunity to shine on flash-guitar numbers like Otis Rush's "All Your Love" and Freddy King's "Hideaway." And Clapton's easy-rolling cover of Robert Johnson's "Ramblin' on My Mind" marked his debut as a lead vocalist. John Mayall may have been overshadowed by his blazing attaché, but he and the Hughie Flint/John McVie rhythm section hold their own throughout. There are better '60s blues albums, but few had greater impact. --Steve Stolder