A bit of background: by 1984, DC had only a few books selling above the comic book equivalent of the Mendoza line. One of those was, of course, Marv Wolfman and George Perez's New Teen Titans, a series which featured a heavy dose of soap opera. Another was the Legion of Superheroes, which also featured a heavy dose of soap opera. Meanwhile, the Justice League of America title was floundering. Batman and Green Lantern had been removed from the team due to events in other series, and the Atom had become, at best, a part-time player. Long-time writer Gerry Conway had recently departed the series, and there seemed a fair bit of creative frustration that JLA was unable to emulate the successful NTT/ LSH model, due to the fact that many of its characters had their own books. You couldn't do anything significant with Wonder Woman in JLA, because she had her own series where she had to be relatively unchanged.
So DC lured Conway back to the book with a plan for radical reinvention - hatched beginning in JLA #228-230. In that arc, the Martian Manhunter returned to Earth from Mars II (where he'd been living for some years) just in advance of a Martian invasion of Earth. Coincidentally this event occurred while Superman, Wonder Woman and the Flash were AWOL. (Their whereabouts would be revealed in JLA #231-232.) This left the JLA significantly below full strength, with Aquaman the only original member still on the team and present. The Martians basically trashed the weakened JLA before being defeated by J'onn J'onzz, with an assist from Firestorm. In the aftermath of the event, Aquaman decided that the JLA had lost its way, and that the world needed a team full of members who were fully devoted to their JLA duties. Thus, using a heretofore-unknown and almost certainly made-up for this story clause in the League's charter, Aquaman disbanded the original JLA. Most of the members went their separate ways, while Aquaman began the process of assembling a new team, beginning with the core of himself, J'onzz, Zatanna & the Elongated Man. Well, perhaps "assembling" is a strong word, as basically he just sat around while a bunch of kids tracked down the team and asked to join up. It really didn't make much sense under any scrutiny. Anyway, the League got four new members, all of whom were younger and/or less experienced heroes - Vixen, Steel, Gypsy, and Vibe, the breakdancing superhero.
The new team lived and operated out of a bunker in Detroit, given to them by Hank Heywood Sr., the Earth-2 Commander Steel who had migrated to Earth-1, gotten old, and gone crazy. His grandson was the new Steel. Hence the "JLDetroit" moniker. It's actually a misnomer of sorts - the JLA moved out of the bunker in issue #246 and moved to New York, where it stayed until the series' conclusion with #261. They were gone from Detroit as long as they were actually in Detroit.
Anyway, the idea was that these new characters were blank slates, and that Conway could expand on their interpersonal relationships and develop them as characters. He rarely actually DID so - he tried, to his credit, but none of the characters really grew or changed during his run. (Conway wrote the book until #255, at which point he was replaced, mid-arc, by J.M. DeMatties. DeMatties wrote the rest of the issues.)
The other big misconception about the Detroit League was that Aquaman was front and center. He was at first, but was actually written out of the series in #243. J'onn J'onzz assumed leadership of the team following Aquaman's departure, and then Batman returned to lead the team in #250. DeMatties did not feature Batman in any of his issues, noting that he was "busy" or "distracted", presumably by the events of the Legends miniseries. Conway alluded in issue #250 to Batman having a secret agenda for rejoining the League, but never revealed what it was.
Conway was successful in adding more soap opera and continuing storylines to what had traditionally been a very episodic series. The craziness of Old Man Heywood was in the background for about a year before reaching critical mass. Zatanna had a lengthy storyline of her own beginning when the League returned to New York, that ended with her departing the team in #257.
Looking back at these issues, the whole conceit of the series makes relatively little sense. The notion that Aquaman, having disbanded the League because it was ineffective in its stated task, would reconstitute the team with newbies and a runaway teenager who robbed fruit stands is patently ridiculous. Fish jokes aside, the dude's bound to have had one of the best Rolodexes in the DCU - why not call up Batgirl, or John Stewart, or y'know... someone other than Vibe? Likewise, the idea that these eight folks (plus Sue Dibny and Dale Gunn) would have anything in common such that they'd live together and all be friends is absurd. The team was mostly ineffective and/or effective by chance - most stories would have the team get trashed, then saved at the eleventh hour by a hail mary from one member.
Despite that, I was 10 when JLA Annual #2 (which introduced the new team) was published, and I totally bought into it. The end of the JLA felt like a momentous event, and I totally accepted that now the new guys were in the comic. I think in those days a lot of the audience was 10 - you could get away with inherently dumb concepts in a way that you can't now. I'm not sure I ever really bought into the idea that these guys were THE Justice League, though - I accepted them as the stars of the book and enjoyed the book but it felt like it's own thing, just with a familiar name.
As you'd expect, DC almost immediately began teasing the return of the originals, bringing Superman, Wonder Woman and the Flash back to Earth in #237-238 (wherein they were rescued by the new team). #240 was a flashback tale of the original team. And in #250 Batman, Superman, and a couple of other originals returned to bail out the new team from imminent disaster, after which Batman stayed on as the leader. Each instance ended with the Detroit League staying on and keeping on, even #250 which was a post-Crisis on Infinite Earths story.
I've assumed over the years that the decision to end the JLDetroit experiment was related to sales. I cannot imagine the book was selling all that well. Luke McDonnell had come aboard as the artist on #245, and though he later did a fantastic job on Suicide Squad, he was a poor fit for the JLA. I suspect Batman's return was meant to give the series a sales jolt, but failed to do so.
Issue #255, Conway's final issue, had begun a new arc bringing the Zatanna plotline to a head. She had been captured by a cult leader named Adam in #250, and subsequent issues had shown him harvesting magical powers from her in some rather disturbing scenes. #255 revealed Adam to have acquired nearly Godlike powers, and the stage appeared to have been set for another showdown between the hilariously outmatched JLA and a powerful foe.
Then #256 arrived, with DeMatties having replaced Conway, and the series took an abrupt left turn. Adam's acquisition of Zatanna's powers was revealed to have shattered his mind, and the remainder of the next two issues was devoted to Zatanna, J'onn and Gypsy attempting to save him. This culminated in Zatanna leaving the team, having purportedly fallen in love with Adam. If an outsider had to pinpoint the moment DC gave up on this direction, it's likely the dart would land somewhere between #255 and #256.
The final four issues of the series were tied into the Legends crossover, wherein President Reagan had ordered superheroes to withdraw from public life. J'onn, having assumed command of the team (again) due to Batman's absence, reacted by disbanding the team. At the same time, Professor Ivo had decided to gain his revenge on the original JLA by murdering the newbies (a plan that was intentionally nonsensical, as the story itself points out). To that end, he dispatched androids to murder the kiddies, who had now gone their separate ways following the dissolution of the team. The androids successfully murdered Vibe and Steel (though Steel was later revealed to still be on life support so he could be killed again in a later story). Gypsy survived her encounter but chose to return to her family, which I guess was in or near New York for some reason. The final issue featured J'onn and Vixen, the only remaining team members, facing down Ivo. Vixen would also depart the "team" at the issue's conclusion, leaving J'onn alone to respond to an emergency signal.
"The saga of the Justice League of America... ends here." reads the final caption of the final issue, as J'onn races to answer the signal. But it didn't, really - it had ended quite some time earlier, when the original League broke up. Still, the end of the Detroit team was quite affecting, particularly Vibe's death which I thought was exceptionally well-done. Vixen's impassioned departure speech to J'onn at the end of #261 is a little on the melodramatic side, but it worked primarily because it lent the deaths of Vibe and Steel some gravitas. You know by now how these things go - when editorial gets sick of a character they have them killed off, and no one really seems affected by the death. DeMatties showed Vixen as profoundly affected by the deaths of these two kids - a tragic way to end that incarnation of the League, but a valid one.
In many ways the whole idea was wrongheaded - the Justice League is supposed to be DC's best and brightest, and this demonstrably was not that - but if nothing else, this run worked for 10-12 year old me, and I think it holds up reasonably well if one is willing to suspend disbelief over the absurdity of the concept. Vixen's disillusionment at the end felt almost like meta-commentary for the series itself - enthusiasm dashed, a dream destroyed. Perhaps it was that daring enthusiasm that gives this run its unique place in Justice League lore. We don't talk about the post-Zero Hour League anymore, right? So for those encountering this run for the first time (I expect an Omnibus once the Vibe series takes off!), or for those inclined to judge it harshly as a misstep - judge it if you must, and find it wanting if you will, but take a moment to appreciate its audacity.