Prior to becoming the dynamic, Southern California juggernaut of the mid-’70s, Fleetwood Mac was far more erratic (and sometimes, far more interesting). The band was formed by drummer Mick Fleetwood and bassist John McVie back in 1967 and, in their earliest incarnation, were influenced by the stunning, self-critical guitar work of Peter Green.

Before forming Fleetwood Mac, Fleetwood, McVie and Green were all members of John Mayall’s Bluesbreakers, and recorded a handful of songs together.

The first edition of the band was not (just) about the blues. Green made his case with fluid, delicate, raw emotion on classics such as “Albatross” and “Man of the World,” while…next to him, slide guitarist Jeremy Spencer lent it all a dirtier, more traditional sound. Then along came Danny Kirwan and the songs opened up to new melodic possibilities.

It was a brief stability. By 1970, Green had left, and Fleetwood Mac was changing members and styles, slowly progressing from blues toward what was surprisingly commercial music with pop sensibilities. But long before the arrival of Lindsey Buckingham and Stevie Nicks—and the significant shift of the band‘s persona as the calendar turned to 1975—Fleetwood Mac defined late ’60s British blues.

New musicians came and went. Among them were keyboardist/vocalist Christine McVie (John’s wife, original name Christine Perfect), who would become a fixture of the band during its most successful period, and Bob Welch, an American singer-songwriter, who stayed with the band from 1971-74 before moving on to a successful solo career.

“Albatross” (1968)

This delicate instrumental, built of epic guitar lines and very slow, tide-like rhythm, captures Green at his most restrained. The track, the band‘s only #1 single in the U.K., subtly changed their impact and influenced a whole generation of British guitarists.

“Black Magic Woman” (1968)

Two years before Santana made it big worldwide, Green, McVie and Fleetwood earned a modest U.K. hit with this early single. Green‘s vocal and stinging guitar led the mysterious, seductive song, woven over an elusive rhythm. It’s a fine example of his superb style at just 21 years of age.

“Shake Your Moneymaker” (1968)

This lively version (is there any other kind?) of the 1961 Elmore James song was buried as the fifth track (of six) on side one of the group’s debut album. From the sound of things, it appears that a good time was had by all during the recording process.

“Need Your Love So Bad” (1968)

This blues cover of the 1955 Little Willie John song features a member of the band Chicken Shack—John McVie’s wife, Christine—who appeared as a session keyboardist on several Mac tracks before joining the band full-time in 1970. The non-album track was released as a single, reaching #31 in the U.K. and later appeared on several compilation albums.

“Stop Messin’ Round” (1968)

A lean, high-velocity shuffle and a perfect showcase for the band in its rawest early form. The tidy and percussive guitar leads the way into a glorious, full-tilt blues stomp, heralding Green as one of the tightest and most economical blues guitarists out there. A perfect sonic shot of adrenalized energy.

“Man of the World” (1969)

Green’s fragile vocals are complemented by sparse instrumentation that leaves each word exposed, and it stands as one of the most affecting of his career. It is profoundly personal, conveying his lonely state-of-mind. Decades later, Fleetwood told Rolling Stone, “We had no idea that he was suffering internally as much as he was.” It all added up to becoming a popular hit in the U.K., reaching #2 there.

“Oh Well (Part 1)” (1969)

Another big U.K. single (#2) was also the band’s first to chart on the Billboard Hot 100, reaching a modest #55. (They wouldn’t return to the U.S. singles chart until 1975 with the beginning of the band’s significant run with Lindsey Buckingham and Stevie Nicks.) The classic track—it’s been a frequent cover—begins strongly and maintains a relentless intensity. The delivery of pure acoustic blues breaks down to meet jagged electric riffs and Green sets off on one of his most assertive and straightforward efforts.

“The Green Manalishi (With the Two Prong Crown)” (1970)

Green‘s last masterpiece with the band was written in time of severe mental anguish. “The Green Manalishi” is said to symbolize his freaky visions of “money dog” and his fight against the increasing riches (greed and control) of the band’s other members. A #10 success in the U.K., it is often regarded as a heavy metal blueprint. Judas Priest recorded a cover version of it in the late 1970s, which helped the “grinding riff” reach a far larger American audience.

“Rattlesnake Shake” (1969)

Kirwan‘s presence added a greater depth as a guitar duo. The serious/aggressive sound became a staple of their shows, usually running from 15–20 minutes. Fleetwood has acknowledged that he’s the subject of the Green composition as an homage to male masturbation. In fact, he’s named in the lyrics: “I know this guy, his name is Mick, now he don’t care when he ain’t got no chick. He do the shake and jerks away the blues.”

“Love That Burns” (1968)

This song is proof that sometimes the less you play, the more you can convey. It never gained much traction in America. The vocals have a mournful quality, elevated by an atmospheric, almost cinematic, horns and piano-filled production that makes up much of the instrumentation.

“Coming Your Way” (1969)

This track, the leadoff number from their third album, Then Play On, is a reflection of the complex, double percussion groove that would become typical of the Kirwan years. It displays his “brighter, more melodic sensibility” by combining his vibrato with a new, folk-rock-oriented sound. The song is of a time when the band was still rooted in blues, but starting to surround itself with the experimental blues-rock of the early ’70s.

Green departed the band in 1970. It took years—he was diagnosed with schizophrenia and underwent shock therapy—but he eventually emerged and found his musical footing and was still performing in 2018.

On Feb. 25, 2020, Green was celebrated in London with an all-star event billed as “Mick Fleetwood and Friends Celebrate the Music of Peter Green and the Early Years of Fleetwood Mac.” The performance featured such acolytes as Christine McVie, David Gilmour, Pete Townshend, Billy Gibbons, former Rolling Stones bassist Bill Wyman, Steven Tyler, and others. Original Fleetwood Mac member Jeremy Spencer made a surprise appearance. Green was not present.

Five months later, on July 25, he died at age 73. His recordings with Fleetwood Mac are available in the U.S. here and in the U.K. here.