Originally, there was no "cave" as such; in Detective #33, Bruce slips into his "secret laboratory": The concept of hidden rooms and sliding panels was a staple of boys' fiction from Edgar Rice Burroughs through the Hardy Boys and beyond.
In Detective #63 we learn that Batman parks the Batmobile in the barn located on his property and then enters Wayne Manor through an underground tunnel.
The next time around, the only thing we saw was the Trophy Room, and it certainly appeared to be located above ground: That's from Batman #12 (August-September 1942). Later, in that same issue, we got the very first view of the cutaway of Wayne Manor, showing the underground "hangars": As you can see, it's just a glorified basement, with no indication of stalactites or bats.
In Batman #16, Alfred stumbles upon the sliding panel that leads to this:
In the Batman serial from 1943, the second episode was entitled The Bat's Cave. Batman and Robin bring a crook back there and interrogate him, with the bats flying about so unnerving the criminal that he tells everything that he knows.
Finally, in Detective #83, we got our first real look at the Bat-Cave in the comics: The intruder in the Bat-Cave turns out to be their butler, who's exercising. Yep, this issue also saw the debut of the slender Alfred.
Jerry Robinson (along with Dick Sprang) was one of the two major Batman artists of the early 1940s. As I mentioned in a recent post, Robinson was the master of light and shadows. Here are some examples from Detective #76: Characters outside the light portrayed in purple? That's Robinson's signature; there are probably a dozen examples of it in this issue alone. Check out this night-time street scene: Notice the nice little details there; the storm sewer, the manhole cover, the car or truck coming into the picture from the left, the small blotches of light in the inky (literally in this case) darkness. Like a movie director, Robinson knew where to place the camera: More terrific shadow work here: Notice how the coloring on this panel conveys the three-dimensionality of the city: The lighter, pastel blue in the background makes it clear it's behind the more solid blue which is behind the purple building. It's the same concept that ACG would exploit years later in its "TrueVision" 3-D comics.
Can tell us something. Consider this tale: Now of course the notion of anybody living in a glass house is rather absurd; there is the obvious problem of privacy. In the story, a crooked developer of steel houses is trying to drive his glass-house competitor out of business with thugs. Eventually the steel house is revealed as unsuitable as it attracts a lightning bolt, which causes devastation to the structure.
Crazy story, it's true. But it's reflective of its era, the immediate post-WWII period. After the war ended, there was a tremendous pent-up demand for housing. Very few new homes had been constructed during the Depression or the war years. Now all those servicemen had returned home from Europe and the Pacific, and they were getting married and having kids, sparking the great postwar baby boom. They needed housing, and developers rushed to fill that need. Levittown, and many more suburbs like it, sprang up all over the landscape.
You can say similar things about this story: Most people snort at the idea of Ace, the Bathound, although as I mentioned here he was valuable enough that he appeared on many Batman and Detective covers of that era; surely more than any character other than Batman and Robin themselves. Why did Bathound arrive in June 1955?
Again, it reflected what was happening in society. During the depression, many people had moved to the big cities, where the few jobs that were available could be found. Now that suburbia had sprung up (and America experienced an era of greater prosperity), people began buying dogs for their kids. You can see signs of it all over pop culture, if you look hard enough. Not only did Superboy get his own dog a few months earlier (Krypto), but the long-running TV show Lassie began in 1954. Remember Old Yeller, the Disney tear-jerker? DC had a long-running comic entitled Rex, the Wonder Dog that lasted from for 46 issues from 1952-1959.
What about the plague of aliens that arrived during the Jack Schiff era? The 1950s were filled with reports of flying saucers, of alien invasions, with movies like The Day the Earth Stood Still, or The Blob, or Invasion of the Body-Snatchers. To a certain extent, I think this was caused by the expanding field of rocketry; as we began to look outward, we realized that other worlds might be doing the same thing.
A lot of these things look crazy or zany from our lofty perch in the 21st century. But they reflect their times.
In the beginning, there was no need to fill in the legend, because there was no reason to suppose that Batman would become an enduring part of the landscape. Comic heroes came and went. Captain America, the Human Torch, the (Alan Scott) Green Lantern, the (Jay Garrick) Flash, the Black Terror... all those characters were gone from the scene after about 1949.
But when Batman did not join them in limbo, the writers and editors began filling in the legend for us. Obviously the first salvo in this effort was the expansion of Batman's origin tale in Batman #47. Over the next decade there were many stories that contributed to rounding out our understanding of the Caped Crusader, and for some reason, most of these tales were published in Detective Comics.
In Detective Comics #205, Robin asks Batman about how he initially found the Bat-Cave and: And although elements of the story have changed significantly (for example, Bruce did not buy Wayne Manor but grew up it), the idea that he discovered the Bat-Cave by falling into it has endured, being depicted in Dark Knight Returns and in the Batman Begins movie.
The next bit of legend filling came in Detective #226's When Batman Was Robin. We learn how Batman first trained to become a detective: As with several other stories in this era, this one contains some parts that contradict the legend. For example, Bruce explains that his parents were abroad that summer, but in the story he appears to be 15-16 or so, much older than most origins show him when Thomas and Martha Wayne were murdered.
Realizing that he needs to keep his identity secret, Bruce decides to wear a colorful costume (very much like Robin's down to the "R" monogram on his chest, so that Harris won't find out his real name. As Bruce learns detection, he must also be careful to avoid giving Harvey clues to his real name: Of course, avoiding one clue means giving another; Harris learns from that exchange that Bruce's parents must be fairly wealthy. Over the course of the story, Harris teaches him many lessons, and in the end discovers his real identity. Harris explains in a letter (sent upon his death): Simply wonderful.
The concept of various experts training Bruce in the skills he would need as Batman was continued in Detective #227. Barret Kean is getting too old to play a leading role on stage or screen, so his agent suggests setting up a school to teach young actors about makeup. And fortunately, he has an old pupil who can vouch for his abilities: And after an interesting case involving an attempt by the underworld to discover Batman's true features, there's a very similar ending to the prior issue: Another one of Batman's experts is Lee Collins. Collins threw the boomerang as part of a sideshow act. He impressed Batman by helping him catch a crook, and: So not only did Collins teach Batman how to throw, but he also created the very first Batarang!
I believe there is a story out there about the guy who taught Batman lock-picking as well, but I can't quite put my hands on it at the moment. It's possible that it's a more recent story. Anybody?
Another aspect of the legend was filled in with Detective #235. This issue includes the famous story, The First Batman. We learn that Thomas Wayne had worn a bat costume and fought crime himself, while Bruce was still a youngster. It happened that some crooks showed up at a masquerade ball which Thomas attended. This story also revealed that Bruce's parents were not killed by a happenstance robber, but that it was a planned revenge murder by one of the crooks Wayne pere had apprehended.
Detective #265 contains what appears to be the final story of the "Fill In the Legend" era, with Batman's First Case. We see the troubles Batman had capturing his first crook, and the lessons that he learned from his experience. Incidentally, Bill Jourdain pointed out last summer, that particular story is a swipe from a Golden Age Robin story in Star Spangled. It was also the first issue published with the editor credit of Jack Schiff, which may (or may not) explain why it was effectively the end of the Fill In the Legend Era of Batman. By all accounts, Schiff was the de facto editor for years before that. And yet, from almost the moment he took over the Batman family officially, the stories changed dramatically.