Earth-Two. Say it to an older comic fan (raises hand) and watch their eyes well up.
When superhero comics first appeared in the 40s, heroes from the three companies that eventually became DC Comics teamed up and formed the Justice Society of America. The team appeared till the end of 1950, when the superhero genre as a whole started to wither, save for the "Trinity" characters, Superman, Batman and Wonder Woman, who kept right on going.
Six and change years later, DC decided it was time to bring the superheroes back. But rather than revive the existing characters, they chose to create new ones with the same names and similar powers. They started with The Flash, in Showcase #4. As a tip of the hat to the characters of the past, it was revealed that the new Flash, Barry Allen, read The Flash comics, and that was why he was inspired to become a superhero, as opposed to, I dunno, getting to a doctor and having himself checked out after getting doused with chemicals and lightning.
That's a facet of Barry Allen that gets rather short shrift today - he was a comics fan. He read and collected comics, and was inspired to do good by them. More than ever before, this was a hero fans could identify with.
Showcase did very well, and a continuing Flash title soon followed, as did new "Silver Age" versions of lots of other characters. And a very interesting thing happened. DC started getting letters from readers who wondered what had happened to those older characters, and if they could see them again. This rather surprised DC, who assumed that the comics readership was constantly rotating, and that in the past six years all the old readers had long since moved on.
So they had a brainwave. In keeping with the more science-based motif of the new books, they explained that the adventures of the heroes of World War Two took place on a parallel earth, like ours in many ways, but with a slightly different history, namely with superheroes appearing in the pre-WWII era. They even had their own "Trinity" heroes, which neatly explained how Superman, Batman and Wonder Woman could have fought Hitler and still look just the same in the mid-50s.
So Barry Allen met Golden-Age Flash Jay Garrick in the nigh-legendary "Flash of Two Worlds", and started a tradition that would last twenty years. Soon the entire Justice League of America met their Earth-Two counterparts, the Justice Society, and would every year for decades.
They didn't stop there. Earth-Three was an evil opposite of the other earths, with the super-powered denizens their worst criminals. As other companies' comics characters were purchased over the years, they usually got their own Earth, to explain how their adventures could have happened. The Quality Comics characters like The Ray and Phantom lady were put on Earth-X, another "Alternate History" Earth, one where World War Two was still raging into the eighties, which gave their heroes, the Freedom Fighters, a chance to keep doing contemporary stories against the Nazis. When DC licensed the Fawcett characters, They ended up on Earth-S, for "Shazam". The Charlton characters got their own earth for all of five minutes or so, as it was introduced and destroyed mere pages apart in Crisis in Infinite Earths.
Crisis (so important is it in DC History, it can universally be spoken of as a single capitalized word) was intended to "simplify" the "Complicated" history of the DCU. The whole multiple Earth thing was seen as daunting to new readers, which the company certainly wanted to attract. So Crisis wiped the slate clean. There was now only ONE Earth, upon which the JSA fought during WWII (albeit without Superman, Batman and Wonder Woman), and some decades later, modern heroes appeared, some bearing the same names as the earlier heroes.
Of course, that meant that a great number of stories no longer "happened", or happened with different details. Many events happened at a different period, and indeed, even Crisis, which we'd just read, was now substantially different in continuity than as we'd just read it.
The JSA was the biggest casualty of the event. Aside from being slapped into a history they never made, it was decided that the characters were too old for the readership, and in a story released around the same time as Crisis, they volunteered to fight an eternal battle in a magic dimension to stave off Ragnarok.
(Dig the way they drew Earth-Two for a while, with the land and sea-masses reversed. I can only imagine the ecological nightmare of an earth with twice as much land as water...)
After just about the same period of time as their last break from action, the JSA were brought back again and given a new series which was VERY quickly cancelled, to the surprise of the fannish community. They were then soundly put down in a later event, Zero Hour, Crisis in Time, where a number of them were killed in battle.
But you can't keep a good team down. After yet ANOTHER event, Infinite Crisis, the team was revived again, this time under the hand of James Robinson, and shortly thereafter, one Geoff Johns.
Immediately after Infinite Crisis, a weekly title, 52, made the revelation that parallel Earths were back. Not the full-blown multiverse of the past, but a set of 52 Earths, most of which have been identified. They're not the SAME worlds of the pre-Crisis multiverse, but many are very similar. There's a version of the Marvel Family on Earth 5 (instead of "S") alternate versions of the Charlton heroes on Earth 4, and the Quality characters on Earth 10 (instead of "X", the Roman numeral for 10), also featuring Nazi versions of other DC heroes.
Note that while the Pre-Crisis Earths were spelled out, the "Post 52" Earths use numbers. That was a deliberate choice to show the difference between the two versions.
And there's an Earth-2, which features a different version of the JSA from the one on the "main" earth, alternately known as either New Earth or Earth-0. It had the most similar history to its pre-Crisis counterpart. It looked for all the the world to be the Pre-Crisis Earth-Two a world in which the timeline continued on after Crisis. A story Geoff Johns wrote for the JSA annual had Power Girl return there, and we got a look at what looked essentially like Earth-Two would have looked like if it had survived Crisis. tantalizing, to say the least.
Well, now there's been one more event, Flashpoint, and this time, the JSA have been wiped off the board entirely. The first superheroes in the world are the modern versions of Superman, Batman, Green lantern, et al, and what's more, even their histories only go back five years.
Fandom's reaction was white-hot and brutal. Fans were not ready to let these characters get taken away again. But never fear; DC wasn't going to wait another six years this time. Even before the book in which the reboot happened could be released, DC announced that the JSA would indeed be back, in a new project written by James Robinson, and drawn by Nicola Scott.
But didn't they just get finished telling us that the JSA was gone from the new history? Yep. The JSA were moving back to their traditional home, Earth-2.
I'll lay odds some folks wept openly.
But here's the question I've been asking...Is it going to be Earth-2...or Earth-Two?
Either way, it's going be a fun adventure.
In part two of this rambling I'm going to talk about how if they play their cards right, and take advantage of the opportunity of a blank slate, Earth-2 could end being DC's Ultimates universe.