But, long before the Crisis On Infinite Earths happened, the Justice League of America and Justice Society of America were dealing with a Crisis every year.
Let's take a look back, and see how these started....with the return of the JSA!
Crisis On Earth-One
This story was where the JLA's Earth (Earth-1) and JSA's Earth (Earth-2) were named, making this the start of the DC Multiverse. The Crime Champions (villains from Earth-1 and Earth-2) gathered as the Earth-2 villains escaped to Earth-1, then the villains came up with the idea to rob from their own world, and spend their cash on the other Earth. To prevent the heroes from catching onto their scheme, they imprisoned the Flashes of Two Worlds (Barry Allen and Jay Garrick), who had first traversed the Earths.
But, the Earth-2 villains got greedy, and faced the JLA (minus Barry) disguised as the Earth-1 villains, magically trapping them in the JLA's Secret Sanctuary. Using Merlin's Crystal Ball that they had from a previous adventure, they contacted their Flash, who then instructed the JLA how to contact the JSA, whom they teleport to Earth-1 to go face their villains, while the JLA goes to Earth-2 to stop theirs (with Green Lanterns Hal Jordan and Alan Scott going between Earths to rescue the Flashes).
Crisis On Earth-Two
Hourman and the Atom stopped the Fiddler, Dr. Fate defeated Icicle, and Hawkman and Black Canary beat the Wizard on Earth-1, while Martian Manhunter, Green Arrow and the Atom stopped Felix Faust, Batman and Wonder Woman beat Dr. Alchemy and Superman and Aquaman defeated Chronos on Earth-2. But, as the Green Lanterns were freeing the Flashes, a spell placed by Felix Faust and the Wizard trapped both teams of heroes in cages in space designed to neutralize their powers. Still, working together, the heroes escaped, and came back to Earth to beat the combined Crime Champions.
These two issues started an annual tradition of JLA/JSA team-ups, and was the first Silver Age appearances of Dr. Fate, Hourman, Black Canary, the Wizard and the Icicle.
Crisis On Earth-Three
Adding an "evil" Earth to the Multiverse, the Crime Syndicate of America was comprised of villain versions of Superman, Batman, Wonder Woman, Flash and Green Lantern called Ultraman, Owlman, Superwoman, Johnny Quick and Power Ring. These villains defeat the JLA members via trickery (using a magic word to imprison their opponents in the JLA's Secret Sanctuary), and with Aquaman and Martian Manhunter otherwise occupied, the Crime Syndicate goes to Earth-2 to face the JSA (with the JLA having warned them of the villains plans).
The Most Dangerous Of All
The JSA (composed of Dr. Fate, Hawkman, Dr. Mid-Nite, Starman and Black Canary) take on the five members of the Crime Syndicate, but, a new wrinkle of the villain team, that of the heroes disappearing to Earth-3 when they claimed victory over the villains. The Crime Syndicate decide to directly face their Earth-1 dopplegangers, and the JLA beat the CSA, by helping to increase their powers, which makes the CSA defeat themselves by not being able to control their powers. The JLA and JSA trap the villains between worlds, ending their menace.
This pair of stories was the first Silver Age appearance of Starman.
Earth--Without A Justice League
Say, you'd think the JSA's Johnny Thunder would be smart enough NOT to summon his magical Thunderbolt, find the Earth-1 version of Johnny Thunder (who was evil), then lose control of his magical T-Bolt to the villain, wouldn't you? You'd be wrong, as JSA Johnny did. The evil Johnny then used the Thunderbolt to commit crimes, and, to stop the JLA from interfering, send the T-Bolt back in time to stop the origins of Superman, Batman, Martian Manhunter, Flash, Green Lantern and Atom, creating an alternate Earth (not a parallel world) called Earth-A.
The JSAers (Flash, Green Lantern, Dr. Fate, Atom, Hawkman and Mr. Terrific) go looking for their missing Johnny Thunder on Earth-1, find out all that has happened, and try to stop the Earth-1 Johnny disguised as JLAers (Flash, Green Lantern, Superman, Atom, Martian Manhunter and Batman), but fail, with the evil Johnny sending his gang back in time to take the place of the JLA which didn't happen, making his gang into the Lawless League.
Crisis On Earth-A
The JSA quickly defeat Ripper Jones as Superman, Bill Gore as Batman, Eddie Orson as Martian Manhunter, Race Morrison as Flash, Monk Loomis as Green Lantern and Barney Judson as the Atom, because the thugs didn't get any experience with their powers. Evil Johnny creates new villains, Medusa-Man, Absorbo-Man and Repello-Man, which do defeat the JSA except for Dr. Fate, who, after beating them, takes on Johnny's Thunderbolt, with the evil Johnny giving the Thunderbolt one last command...to undo all he had done, returning everything to the way it was before he met his double. Then, only the Thunderbolt remembered this adventure....maybe.
This batch of stories marked the first Silver Age appearance of Mr. Terrific and Johnny Thunder's Thunderbolt.
Crisis Between Earth-One And Earth-Two
The two Earths were having multiple menaces this time....with people mysteriously transferring from one Earth to another, while the Anti-Matter Man headed towards the two Earths, now being drawn together. Solomon Grundy was sent to Earth-1, where he faced the JLA's Flash, Green Lantern and Hawkman with the JSA's Black Canary and Dr. Mid-Nite. On Earth-2, the Earth-1 Batman worked with Dr. Fate, Sandman (returning in his original costume) and Wildcat to stop Blockbuster. The Spectre became aware of the Anti-Matter Man's approach and went to stand between the Earths to try to hold them apart....while, on Earth-1, Ray Palmer (the Atom) was unable to help as his size-control unit on his suit would not function.
The Bridge Between Earths
The Atom is finally able to get involved after he finds the problem with his suit...a space warp machine created by his assistant, Enrichetta Negrini. That machine was also causing the transference between Earths, so stopping it exchanges Solomon Grundy with Blockbuster. Dr. Fate finds out about Spectre's problems, and brings the heroes to him to help against the Anti-Matter Man while Atom and Spectre find a way to restore the Earths to their proper location. Meanwhile, Green Lantern kept Grundy and Blockbuster busy by having them fight each other!
This is Sandman's first Silver Age appearance, but fellow charter JSA member Spectre and later inductee Wildcat only are a part of their first JLA/JSA team-up, having returned in Showcase and Brave and the Bold just before this meeting.
But, there were more Crises for the teams to face, as there were more volumes in this series of reprints!