The return of the Justice Society! The first JLA/JSA team-up! The first "Crisis" story!
The story: "Crisis on Earth-One!" by Gardner Fox, Mike Sekowsky, and Bernard Sachs. A team of bad guys calling themselves the (*snicker*) Crime Champions, consisting of Chronos, Felix Faust, and Dr. Alchemy(ooh, I'm scared!) tell the JLA about some crimes they plan to commit, while on Earth-2 the very same thing is happening with the JSA!
The villains trap the JLA, but they use the crystal ball they got from Merlin, no less(JLA #2), to contact Earth-2 and switch places with the JSA! This leads to the first time these two legendary teams have met. They then split up to take on the bad guys of both Earths!
Roll Call: Superman, Batman, Wonder Woman, Aquaman, Flash, Green Lantern, Martian Manhunter, Green Arrow, The Atom
Notable Moments: Oddly, Batman is not listed in the "Roll Call" on page one, though he has a large part in the story.
It's amazing, when looking back, how the smallest notions can be built into Major Ideas. Not to slight Gardner Fox--at all--while I'm sure this idea of bringing back the JSA was immediately recognized as a good one, I bet mostly it was thought of as a way to fill that month's twenty-five pages. Of course, this whole storyline would serve as the basis for the entire DC Universe, produce countless spin-offs, and the cover by Murphy Anderson would become one the hallmark images of DC Comics. Well done, fellas!