You could say ‘Led Zeppelin II’ was ‘Led Zeppelin’ times two: a diverse yet consistently powerful collection of tracks exemplifying hard rock’s expanding template for the ‘70s -- forcefully straightforward and willfully groundbreaking.

That's quite a feat, given the album’s slow and often-interrupted writing and recording schedule during an eight-month period in which Led Zeppelin conquered the U.S. on tour, setting the stage for ‘Led Zeppelin II’ to climb to No. 1.

The album's lead track, ‘Whole Lotta Love,’ reinvents traditional blues with Marshall-stack power and reached No. 4 (Zep’s highest-charting single), leading the charge for soon-to-be-classics like ‘What Is and What Should Never Be,’ ‘Heartbreaker’ and ‘Ramble On.’

‘Led Zeppelin II’ is also the album where Jimmy Page and Robert Plant – and John Paul Jones and John Bonham too – emerged as hard-rock archetypes that would be emulated and imitated by scores of bands in years to come: the omnipotent guitar god, the golden-haired lead singer, the reserved and cerebral bass player and the wild-man drummer.

From here on out, Led Zeppelin would consistently evolve. The second album's template set the pace for the duration of their career.

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