Synopsis for "The Origin of the Justice League - Minus One!"
While he is looking through the JLA casebook, Green Arrow discovers discrepancies in the established "origin" of the team, and asks for the true story, which Superman and Green Lantern relate with the aid of a videotape account narrated by J'onn J'onzz.
In February, 1959, a panic is generated by the revelation of the presence of Martians (specifically from J'onzz and his enemy Commander Blanx and his followers) on Earth. Unable to cope with the situation alone, the Flash, then a mere fledgling as a super-hero, summons the more experienced Superman, Batman, and Robin to help out.
The assembled champions divide up into groups to search out further Martian activity: Plastic Man, Jimmy Olsen, and the Blackhawks accidentally run afoul of Rip Hunter's newly invented Time Sphere. Vigilante, Robotman, Congo Bill, Congorilla, Lois Lane, and the Challengers have a near-encounter with Adam Strange and the Zeta-Beam
Finally, the remaining heroes discover Blanx and his men, and rescue the captive J'onn J'onzz. The successful team, with the exceptions of Robin, Roy Raymond, and Rex, consists of the same heroes who will make an agreement to unite formally as the Justice League of America some months later; even the future Green Lantern is present, having encountered the Martians in his identity as test pilot Hal Jordan.
Note the use of an actual date (1959) in the narrative. That would place the events 18 years in the past (from the publishing date). An editor's note this is comic book time and that characters have their own ways to stop the clock on aging.