Teen Titans 20...
Ever since Teen Titans 20's publication, it might be more "famous" for what it wasn't than what it was.
The title, Titans Fit the Battle of Jericho, is taken from "Joshua Fit the Battle of Jericho", an African-American spiritual presumably composed by slaves.
A story written by Marv Wolfman and Len Wein would've featured DC's first black superhero, Jericho. Going by most Teen Titans stories, Jericho would probably be just a one-off character and never appear again.
As someone in 1969 probably said, all systems were go. Editor Dick Giordano was on board and Nick was in the middle of inking the story. For whatever reason, at least one of the higher-ups at DC got cold feet. And then the ax fell. The story was not to appear.
The cover had already been printed when the story got axed. So Teen Titans 20 had to have some kind of story that went with the title. However it worked out, Neal Adams famously stepped in to write and pencil a replacement story in a... "nick" of time. A new character Joshua replaced Jericho. The Teen Titans had to foil the plot named Operation Jericho. Nick inked NA's pencils. Considering how far along in the original story this was, the published art is spectacular. And thankfully, some of Nick's art still made it to the published comic. I think pages 12 and 14. Although GCD indicates Sal Amendola drew pages 11 and 12.
A good resource on Teen Titans 20 is the TwoMorrow's magazine, Comic Book Artist 1 which also includes a look at some of Nick's lettered and partially inked pages to the original story. Without knowing more about the story, it appears a few black kids got duped into some kind of nefarious activity. To me, from the art and dialog featured in the article, there doesn't appear to be anything that would've been particularly objectionable, even in 1969.
Nick's art to the original story has been scattered to the 4 winds but I'm lucky enough to have some art to the original story. The cover must have some flavor of what the original story would've been. Artistically, on the cover, Nick drew the Teen Titans in his usual style. But all the other characters are drawn in a more abstract style and looks little bit like the first few pages of the original story.
Still, a few issues later, in Teen Titans 26 (1970), Mal Duncan became DC's first ongoing black character. In 1971, the Black Racer (New Gods 3) and John Stewart (Green Lantern 87) made their first appearances. To the extent that he had his own title, Black Lightning (1977) can be considered DC's first major black superhero.
Green Lantern 87 becomes more significant considering what happened with Teen Titans 20. If Teen Titans 20 just had a more generic cover, maybe DC would've easily moved on to an even more generic story. And it probably would be a much longer time before we had any idea of what happened behind the scenes at DC in 1969.
From Comic Book Artist 1:
Neal saw a more positive repercussion: "I think this incident later sparked the decision editorially to accept the Black Green Lantern, and maybe we should have dedicated that story to Len, Marv and Joshua."
Oddly (or coincidentally or ironically) enough, in Tales of the Teen Titans 43 (1984), Marv Wolfman and George Perez introduced a new character named Jericho, who wasn't black.
Robin was created by Bill Finger, Bob Kane and Jerry Robinson.
Kid Flash was created by John Broome and Carmine Infantino.
Speedy was created by Mort Weisinger and Paul Norris.
Wonder Girl was created by William Moulton Marston, H.G. Peter and Robert Kanigher.