I don’t mean within DC continuity. I mean when, and in what comic, was their first published meeting?
Were these the Earth-2 Superman and Batman? When did the S and B comics transition from Earth 2 to Earth-1, anyway?
Superman and Batman started appearing together in World’s Fair comics during the 1939 World’s fair. After the World’s Fair they changed the title to World’s Finest, which was still running Superman-Batman stories when I was a kid in the early 1960s into the late 1960s.
I’m sure the story of their first meeting has been told man times. Two stories from the 1950s have them meeting by accident when changing into their costumes in the same ship’s stateroom. I’m sure that’s not the earliest meeting, but I;m not ast all familar with the 1930s and 1940s stories.
It would have been about 15 minutes before that. 
hehehe.
In fact, it was on the Superman radio show. In the comics, it was All-Star Comics #7.
The first “Earth 1” stories are generally considered to be in the late 50s, when B and S teamed up regularly in the inside pages of World’s Finest, Supergirl made her first appearance, Batman’s chest emblem had a yellow oval and Martian Manhunter first appeared as a back-up in Detective.
They only appeared together on the cover until circa 1954, though.
Just to clarify: Superman and Batman first met on radio in 1945, and shared several adventures together afterwards on the Superman radio show.
In the comics, there was no big “When Titans Meet” story. They appeared together incidentally in All-Star #7 in 1942, as part of a radio fundraiser for war orphans.
Did Batman know Superman’s secret identity in the early days. If not, when did he first learn it? Was there a story about it? (I’m guessing that Superman would have known who Batman was straight away, as he could easily see through the mask.)
I can’t say for sure about the earliest days, but in the 50’s they knew each other’s identities. In some stories Superman would dress up as Batman, so Batman and Bruce Wayne could appear together.
Oh sure, he SAID that was the reason … .
Batman would have lined his mask with lead, in anticipation of such scrutiny.
And used spaces or lead to spell out “HI CLARK”
There’s a question: can Supes see through lead-based paint?
From the Superman Homepage:
“In a 1952’s Superman #76, written by Edmond Hamilton with art by Curt Swan, Clark Kent and Bruce Wayne share a cabin on an ocean liner. In the darkened cabin, the two try to change into their heroic costumes to respond to a fire. The rising flames illuminate the cabin and both learn each other’s secret identities. They team up to battle one of Superman’s most insidious opponents - the snoopy Lois Lane.”
A very similar story, in a recent Superman/Batman Annual, holds this up in current continuity.
That’s kind of funny. “Somebody finally sees me changing out of my secret identity, and it’s the other world’s greatest superhero! Boy, what are the odds huh? Small world, small world! You need help with that zipper?” 
So Supes and Bats were undressing together in a dark room…I’ve gotta echo Pochacco’s “Oh sure, he SAID that was the reason…”
Man of steel, man of kleenex?
Ouch! 
As I said back up in post #2.
The same scene was invoked in later stories in the 1950s, too. They had their story, and stuck by it.
IIRC, though, a later Superbot story had them meeting as teenagers. Can’t leave well enough alone. And the Frank Miller Batman, of ciourse, doesn’t fit into this continuity at all.
The Superman/Batman Annual that sort of retold the ocean liner story a couple years ago features the Earth 1 Owlman and Ultra Man, as well as Super Woman (who in that universe is Lois Lane). It also features a very thinly veiled version of Marvel’s Deadpool. An odd story; I’m not really sure if it’s in continuity or not.
The scene where Superman and Batman figure out who the other is is pretty funny, though.
[spoiler]Clark Kent and Bruce Wayne, forced to share a room, are arguing when an emergency breaks out. Bruce Wayne points at Kent, says, “I don’t have time for this,” and fires a tranquilizer dart from a device on his wrist, which promptly bounces off Clark’s face.
“The jaw…”
“I vibrate when I have my photo taken. Obscures my features.”[/spoiler]
Batman’s yellow field emblem (calling to mind the bat-signal) did not appear until 1964, IIRC. The change also came with better art (Read: Carmine Infantino) and a more serious focus to appeal to older readers. Sillier elements like Ace, the Bat-Hound (yeeesh!) were forgotten, as were space adventures and aliens dropping in every other issue (slight exaggeration here). The strongest focus, aside from teamwork, was Bat’s prowess as the world’s greatest detective.
The change from Earth-2 flavor Supie to Earth-1 is a VERY complicated story, one requiring at least one whole new thread to cover.
E.g.: Perry White replaced George Taylor before Mxyztplk, let alone -PTLK, was ever heard of!
- “Jack”
The early 'Sixties change was called the New Look.
More changes to the two Batman titles came in '66 by the influence of the TV series.
(Fortunately editors and writers were able to make judicious decisions about how much to adapt to the TV series, and how to do it. Otherwise the titles would look even sillier than during the previous years. I don’t think the TV “camp” (A non-gay version, which included deliberate extreme corniness for laughs) would have fared well in the comics.)
I don’t mean to suggest that 1964’s New Look was the point at which Earth-1 started for Batman. At least, definitely Eath-2 didn’t end that late.
I think it’s even harder to say than for Superman. We at least know that by the inro of Supergirl, and even Brainiac and Kandor the year before the transition was complete.
Many fans have decided that some explanation for the in-between years of Superman continuity was in order.
One of two suggestions was that some of misfit features pointed to yet another Earth, Earth-E. This could stand for Extraneous or E. Nelson Bridwell, a fan-turned-pro.
Getting back to Batman, perhaps the silly phase of late 50’s and early 60’s could be assigned to Earth-E. As I have said, certain elements were forgotten, but nevertheless they don’t seem to fit in with the Golden Age.
- “Jack”