The Eagles weren't even a separate group when they played their first gig together on July 12, 1971. The musicians who would go on to dominate popular music in the '70s and '80s performed together publicly for the first time in public as a backing group for superstar Linda Ronstadt — and at a pretty unexpected venue.

Don Henley, Glenn Frey, Bernie Leadon and Randy Meisner were all veterans of various groups in Southern California's burgeoning country-rock scene in the early '70s when they were picked to back Ronstadt in a new band — in fact, that's why they were selected.

Henley had performed as a drummer in a group called Shiloh, which Kenny Rogers first discovered in Dallas and brought to Los Angeles to record, while Frey had worked in a duo called Longbranch Pennywhistle with J.D. Souther. Meisner had played in Rick Nelson's Stone Canyon Band, and Leadon had performed with the Flying Burrito Brothers prior to playing with Ronstadt, who hand-selected them to form a group of country-rock "all-stars" to back her on her Silk Purse Tour in 1971.

The new group made its debut backing Ronstadt during a performance at Disneyland on July 12, 1971, but the chemistry between the band members was so undeniably special that Henley and Frey soon approached Ronstadt to inform her of their intention to split off and form a new band of their own with those musicians, leaving her to once again hire an entirely new group.

Though the lineup was short-lived behind Ronstadt — the Disneyland show was, in fact, their only show with her — the sound of them playing together with her was immortalized on her self-titled third studio album, released in 1972. All four original Eagles appear on various tracks of that album, but they would waste no time making a mark of their own.

The Eagles released their self-titled debut album on June 1, 1972, and they were successful straight out of the gate, scoring hits with "Take It Easy" (which Frey co-wrote with his friend and then-neighbor, Jackson Browne), "Witchy Woman" and "Peaceful, Easy Feeling." The Eagles reached No. 22 on Billboard's US Pop Albums chart and was certified Platinum after selling more than a million copies, setting the band on a course to become one of the most successful in rock music history.

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