Though not the overlooked masterpiece that collectors have often portrayed, Horses still offers considerable appeal, particularly as a brief, one-off studio project. The core of the ensemble behind this album originated with the strong mid-'60s bubblegum-psychedelic group the Rainy Daze, whose camouflaged tribute to marijuana, "Acapulco Gold," reached the lower rungs of the Top 100 in 1967. After shifting to Los Angeles in 1965, Denver radio host David Diamond launched a fresh rock format known as "Boss Radio" and brought the band along. Finding the rigid, hits-only constraints of his new position unappealing, Diamond transferred to KBLA, where he soon emerged as one of L.A.'s most influential on-air figures through his psychedelic program The Diamond Mine, an early example of the freer, album-oriented underground FM style. Frank Zappa counted himself among the show's regular listeners, and Diamond's recommendation to the Doors helped produce a global success with the shortened cut of "Light My Fire." He also introduced listeners to tracks including the Seeds' "Pushin' Too Hard," Iron Butterfly's "In-a-Gadda-Da-Vida," Nancy Sinatra's "These Boots Are Made for Walkin'," the Stone Poneys' "Different Drum," the Rolling Stones' 17-minute "Goin' Home," and, naturally, the Rainy Daze's "Acapulco Gold." Diamond played a pivotal part in the band's trajectory by persuading a then-unstable Phil Spector to take them on under a management agreement; when Spector's expected promotional campaign failed to materialize, Diamond secured a contract with UNI that issued the group's impressive LP. The driving forces within the quintet were lead vocalist and guitarist Tim Gilbert and lyricist John Carter, who matured into one of the period's more distinctive minor songwriting partnerships. Their compositions yielded a major Number One success for Strawberry Alarm Clock with "Incense and Peppermints," along with placements for Yankee Dollar and the compelling David Axelrod-produced West Coast act Hard Water (the disguised continuation of fellow Colorado surf and instrumental veterans the Astronauts), yet Horses remained Carter and Gilbert's primary focus—a quasi-psychedelic hard rock outfit they assembled from the ground up with Diamond after the three had all moved to San Francisco in 1969.
Following the Rainy Daze's dissolution after a string of later singles on the Turtles' White Whale imprint, Carter and Gilbert had already completed a full album's worth of material and simply required musicians to record it. Joining forces with Diamond, they conducted auditions that ultimately brought together Dave Torbert on bass, Scott Quigley and Matt Kelly on guitars, Chris Herold on drums, and lead vocalist Rich Fifield. Fifield departed partway through the sessions, replaced by the then-unknown 18-year-old Don Johnson on his debut professional engagement. The resulting self-titled album stood as a solid achievement, blending sly countercultural references—such as the veiled sexual content of "Class of '69"—with hippie-inflected country touches inside its hard-rock framework, though it appeared on White Whale precisely as the label began to unravel. (Gear Fab reissued it on CD in 2003.) Horses dissolved not long into 1970, but two of its songs, "Overnight Bag" and "Asia Minor," found renewed life when Kingfish recorded them for the band's debut album. Kingfish itself had been formed in 1975 by Herold and Torbert (who subsequently joined New Riders of the Purple Sage) together with the Grateful Dead's Bob Weir. Kelly likewise contributed to several Dead releases during the '70s and issued two solo albums on the group's Relix label; earlier he had belonged to Gospel Oak, which cut a 1970 LP. Quigley went on to perform with the Sammy Hagar Band before dying from a drug overdose. Gilbert later cut a pair of singles under his own name, while Carter, besides continuing to supply songs for other artists, rose to become a leading producer at Capitol Records, overseeing projects for the Motels, Bob Welch, and Tina Turner (including the international hit Private Dancer). Diamond persisted as a prominent radio personality and also achieved success as a novelist. Johnson, naturally, attained global fame as a film and television actor, above all through the emblematic '80s police series Miami Vice.