Well, I received my script book in the mail, and read through all the stuff about a spinoff series. My head is spinning from all the different permutations of what might have been. As far as I can tell, based on both the script book and JMS's public statements over the years, the timeline goes something like this:
From the very beginning (as in, even before Season 1) JMS makes some comments online to the effect that, should B5 be a big hit, he has an idea for a side story that could be used for a spinoff, but he doesn't think this is very likely.
Some time in the fall of 1996 (right in the middle of production on Season 4), Warner Bros. asks JMS for ideas on a spinoff series. Because of PTEN folding, it doesn't look like they're going to do a Season 5. But they'd still like to try to do a spinoff series. JMS proposes a series concept that he describes as "Camelot in Space". A series that would take place in the early days of the ISA (chronologically, just after the conclusion of B5), that would feature the Rangers going out and helping to maintain order in the galaxy....giving the various worlds the choice of "joining us, staying neutral, or fighting us". JMS describes it as "Arthurian".
Warner Bros. asks JMS to come up with some kind of gimmick that they can use as a hook to sell the series. JMS suggests the idea of a plague that will wipe out all life on Earth within five years unless a cure is found. (Based on his description of events, it sounds like he came up with this idea on the fly in the middle of a meeting with WB.)
The script book includes two memos written by JMS around this time, though it's unclear which one came first. One memo (which JMS really just intended as notes for himself; not for anyone else) outlines story elements that could be added to the existing arc for Season 5 that would lead into the spinoff series. JMS was trying to argue that Season 5 could be used as a setup for the spinoff series, and that this is why, if TPTB wanted to produce the spinoff, they should also produce a Season 5. These added story elements were ultimately never included in Season 5. One of the elements was the introduction of a Technomage character, who would have pretty much the same role that Galen ultimately had on Crusade.
The second memo was the pitch for the spinoff series, titled “Babylon 5: Rangers”. It's all about the Rangers and the “Camelot in Space” idea. There is no mention of the plague storyline. The cast of characters includes such B5 characters as Sheridan, Delenn, G'Kar, Franklin, and Marcus. The story makes sense only if Season 4 ends in such a way that Marcus is alive and Sheridan does not become president at the end of Season 4. (And remember, this was written when JMS was in the middle of writing Season 4, so that's cutting things close in terms of how the season would end.) It's unclear whether the idea of featuring so many of the original cast in the spinoff was always part of the plan or not.
As early as November 1996, JMS mentions that the name of the spinoff series would be “Crusade”. Or more specifically, “The Babylon Project: Crusade”:
http://www.jmsnews.com/msg.aspx?id=1-12026&query=crusade
By at least the end of 1996 (perhaps much earlier, I'm not really sure), JMS has revealed that the spinoff series will deal with the Rangers:
http://www.jmsnews.com/thread.aspx?id=_=Crusade= Spinoff?
As early as February 1997, JMS has publicly mentioned the plague storyline in online discussions:
http://www.jmsnews.com/msg.aspx?id=1-2474&query=crusade
Also as of February 1997, JMS has mentioned some possible new characters for Crusade. This is refered to elliptically here:
http://www.jmsnews.com/msg.aspx?id=1-11012&query=crusade
but I can't find the original post that discusses the new characters. In the aforementioned post, JMS says:
BTW, that new characters were mentioned does not exclude any current cast members...doesn't include them, either, but bottom line, that ain't a complete list of characters. There's room and flexibility in there, depending on what happens.
Throughout 1997 and into early 1998, JMS repeatedly mentions that the greenlight for Crusade could come at any time, and that he's hopeful that it'll come soon, but nothing is certain.
As late as November 1997, JMS is still describing Crusade as “the Rangers series”:
http://www.jmsnews.com/msg.aspx?id=1-3534&query=rangers series
April 1, 1998: As production on Season 5 is wrapping up, JMS responds to rumors about cast turmoil and actors being upset that the show is ending:
http://www.jmsnews.com/msg.aspx?id=1-1643&query=crusade
http://www.jmsnews.com/msg.aspx?id=1-10559&query=crusade
In that second post, JMS says:
One or two cast members may transition over into Crusade, assuming it goes ahead, but that show *has* to be its own show, it can't be just a repackaged B5. (And I'm referring to regulars here, there's plenty of room for guest-starring roles for nearly all of our characters at one point or another, plus the likelihood of more B5 TV movies, plus the real possibility of a B5 feature.)
A few days later, TNT confirms that Crusade is being greenlit. You can read the press release here:
http://homepages.ge.ucl.ac.uk/~jmorley/gold_channel/crusade.html
There is no mention of casting. The Drakh plague storyline is featured in the press release, but there is no mention of the Rangers or the empire building stuff that JMS apparently talked about in his original pitch a year and a half earlier. However, the title “Crusade” remains, and the series itself turns out to include a lot of Arthurian iconography. The unfilmed scripts (released in 2000) reveal that the “real storyline” of this version of Crusade deals with Earth's covert use of Shadowtech. Again, something that's quite a bit different from the original pitch.
After Crusade is cancelled, there is a second attempt made at a B5 spinoff a few years later. This one features the Rangers.
That is the timeline as far as I can reconstruct it. It bears repeating that the ad for Script Book 10 appears to be a bit misleading, in that it leaves the impression that the “B5: Rangers” series was an entirely different animal from “Crusade” as we know it. But, based on what I've shown in this post, it actually looks like the former evolved into the latter. (Several elements got carried over, including the plague storyline initially being suggested as a gimmick for the Rangers series ultimately being a gimmick for the non-Rangers series that we ultimately got.) And then a few years later, when JMS had a second crack at a B5 spinoff, he chose to go back to his original idea.
The biggest question I have is what happened with regard to the idea of bringing back so many of the original cast. At what point was that idea dropped? (If anybody can find that Feb. 1997 post about new characters, maybe that can provide some clues.) Also, does any of this stuff bear any resemblance to what JMS was talking about way back in 1993, when he was already talking about a “side story” that could be spun off of B5? Or is that yet a different series idea?
