What kept the Shadows from attacking Babylon 5?

Question

According to the 3rd and 4th seasons the Shadow ideology was about bringing out the best of the younger races by provoking conflict between them (or something along those lines). But at the beginning of the series those younger races were a hair's breadth from clashing with each other, and even one of the Shadow ships could likely have cut B5 in two with a single shot (I'm basing this on how they were seen wiping out Narn battle stations and warships so easily with little, if any damage in return).

So what stopped them from doing it? Were they still recollecting their forces? Did they not want to tip their hand too soon? Were they just not informed of current events?

Answer 1

Nothing. They did. In War Without End, B5 was destroyed by the Shadows.

Back on Babylon 5, C&C detects a distress call coming from sector 14, which surprises Ivanova since it has been quarantined for nearly 3 years after Babylon 4 disappeared there. Lt. Corwin plays the message, and it is Ivanova's own voice, which a computer voice scan confirms. "They're coming through," Ivanova's voice cries out desperately, "repeat, they're coming through. This is Earth Alliance Station Babylon 5. They're all over the place! They're killing us. Can anyone hear me? They're killing us!"

But fortunately, B4 pops into existence and, if you don't know, I'd best not spoil it, but...

"And that is about to change," Delenn replies, changing the image again. "This was recorded shortly before the station first disappeared six years ago. As Babylon 4 neared completion, the allies of the Shadows recognized it for what it was, and sent these ships to destroy it. Striking without warning, they would have succeeded in their attack, but something stopped them." A ship appears on the screen, firing at the Shadow fighters.

So Sinclair and co have to save B4 in order to ensure the Shadows get a pummelling in the first Shadow War which results in them being too weak to attack it again in the present.

Delenn answers that, without Babylon 4, the Shadows would come out of the last war much too strong -- something with which Sinclair agrees. Sheridan asks where the information came from, but Sinclair just says a reliable source. Marcus says that, if Sinclair believes it, he believes it. Delenn says that, if they do not proceed, in the next major attack by the Shadows, Babylon 5 will be destroyed

And so, Zathras helps Sinclair tie up a few interesting story ends in what's possibly the best episodes of all of B5. They have Zathras in them after all.

As for Mr Straczynski, he gives the following answer to the question:

Why didn't the Shadows destroy B5 before it went online?

B5 wasn't destroyed because it wasn't the one that would be taken back. Yes, the prior stations would've looked more like B4 but they were sabotaged very early in the construction process.

Answer 2

There's at least two big ones, both of which aren't apparent until later in the series, and one smaller one, which you've posited as a possibility.

The smaller one is that, yes, they were still collecting their forces. There were several episodes where that was a plot point; for example, 2x05, The Long Dark, and 3x08, Messages from Earth.

Spoiler Warning, the entire rest of this answer builds off of the Season 3 finale.

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The Shadows and Vorlons stayed behind to shepherd the younger civilizations, but have drastically different ideals on how to go about it. So the younger races get used in a galaxy-wide chess match, both sides trying to use them to prove that their ideal is the correct one.

For the Shadows, conflict is what drives civilization to greater heights. They sow discord, the younger races fight each other, the strong survive and the weak rebuild stronger than before. If the Shadows openly attacked Babylon 5, they would position themselves as a strong, common enemy, that the younger races would have unite against lest they be destroyed as well - and with the Vorlons already participating in the peace talks on the station, it would likely not go well overall.

The millennia-long conflict between the Shadows and Vorlons also had its own rules, which Kosh violated when Sheridan convinced him to act directly against the Shadows, and led to Kosh's death in retaliation. If the Shadows acted directly against the station, either Kosh or Ulkesh would have been caught in the line of fire, and similar retaliation would likely have been necessary.

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Lastly, it just wasn't necessary to achieve the Shadows' goals. The peace on Babylon 5 was tenuous enough as it was, all they had to do was act as mercenaries with Mr. Morden as their front man, and the Narn/Centauri war erupted anew. They only bothered to do so by the end of Season 3 because several things happened during that year that showed just how much of a threat Babylon 5 was:

• The White Star (and its superior technology) was spotted helping Earth
• The Rangers start acting openly
• Delenn convinces the Grey Council to stand with Babylon 5 against Earth (not revealed until much later to be manipulated by or working with the Shadows)
• A transport for Shadow ship seeds is hijacked, and stored at Babylon 5, which leads directly to figuring out the primary weakness of Shadow ships

The very next episode after the hijacking mentions that the Shadow ships are attacking openly, but also mentions that their targets seem random - even then, Babylon 5 isn't a target. It's not until later that they realize the whole point is to drive the survivors together and create more chaos.

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Then comes War Without End, where the distress call from a possible future arrives. See my answer here for an explanation about that little bit of weirdness. But that future was averted, so an attack on the station is further delayed until the finale. (Note that this ties directly to the "gathering forces" possibility mentioned in the question)

But the events of the finale cause such upheaval that the attack gets called off - as G'Kar says, the Shadows believe that Babylon 5 is no longer a threat.

Answer 3

The answer is simple:

Babylon 5 served their purposes.

The Shadows were agents of chaos, shepherding the other races, encouraging them to grow, and so forth. They need to have the ability to network in order for Morden to make his devil's bargains with Mollari and so forth. Babylon 5 did not necessarily serve the Vorlon's purposes.

Remember, aliens had very, very little contact with each other prior to Babylon 5. They didn't have regular ambassadorships on other worlds. The Babylon project was a revolutionary first step in bringing these previously very separate alien races all into one place - and that actually works to the Shadows advantage! Morden gains entré into the very highest levels of the Centauri Republic precisely because Babylon 5 existed (1x13 - Signs and Portents). For much of the show, the league of non-aligned worlds are in complete chaos - because all of them were making their own bargains with the Shadows. (quote from 3x15: Interludes and Examinations)

BRAKIRI: Their technology is too far advanced beyond our own. We cannot defend ourselves against this new enemy without help.
BRAKIRI: Is there anything that Earth can do? My people back home have their own problems right now.
SHERIDAN: Since we declared independence, we are not exactly in the position to ask them for anything. Everyone's on their own. I sometimes think that was the intent.
BRAKIRI: Our military is hopelessly outnumbered. We lost many ships in our recent war with our neighbors.
SHERIDAN: Now you're all in the same position, unable to defend yourselves. I can't believe you trusted the Shadows when they said they were on your side. They just wanted you to waste your resources fighting each other.
BRAKIRI: We thought they recognized our value over theirs.
SHERIDAN: It's not about value. It's. I don't know what it is. I don't know what the Shadows want exactly but they are not on anybody's side but their own.

The reason that none of this logic applies to the previous four Babylon stations is that they were recognized as the miracle station that saved the Vorlon side in the last war. All of the above advantages were not worth the possibility of destroying that station and changing history.

This was capped off by the Shadows attempt to turn John Sheridan in the Season 3 finale. If Sheridan decided to join the Shadows cause, having Babylon 5 would have been an enormous advantage for them (quote from 3x22 - Z'ha'dum)

JUSTIN: Everything depends on getting the other races to fight each other to create conflict in order to promote growth and evolution.
JUSTIN: By getting them to cooperate, you are working against that goal. When this starts, there's always someone who tries to organize the other races.
JUSTIN: You've done it. That's a commendable achievement. But as far as our goals are concerned, unproductive.
SHERIDAN: So why don't you just kill me?
JUSTIN: Doesn't work. Somebody'd just come around and replace you. That's always been the trouble with creating martyrs. We brought you here hoping you'd understand us. Work with us, not against us.
JUSTIN: You're important. You're what they call a nexus. You turn one way and the whole world has a tendency to go the same way. Let go of those other races. You can't hold them together. Evolution will be served one way or another.

If Sheridan had rejected the deal and also not destroyed their largest city, Babylon 5 likely would have been destroyed right then. But remember, they also captured Garibaldi right as this happened. Perhaps they thought that with Sheridan dead (they didn't anticipate him being saved by Lorien) and Garibaldi brainwashed, they still could have used the station to serve their own purposes. And then, the Vorlons started cleansing (quote from 04x06 - Into the Fire):

SHERIDAN: You're destroying whole worlds!
VORLON: The others are a disease. You have given us the opportunity to eliminate it. We are grateful. Why do you oppose us?

Answer 4

(Please pardon the spoiler blocks.)

Early on,

Sheridan was seen as a possible ally. During ‘Z'ha'dum’, when he asks straight–up why the Shadows hadn't killed him yet, Justin informs Sheridan that it would be unproductive to make him a martyr.
Until that time, during the first three seasons, the Shadows weren't interested in B5 — they wanted Sheridan. It was only then that they were preparing to attack B5 directly — until the battlecrabs were called to fall–back, in response to Sheridan's own attack on Z'ha'dum with the thermonuclear weapons carried by the first White Star.

So, there we have one explanation. What about later?

Soon after — during the beginning of the fourth season, — the Shadows and the Vorlons begin cleansing the galaxy of those who've shown allegiance to the other. The Vorlons are first targetting planets which have held, or are holding, contingents of Shadow forces.
The Shadows, meanwhile, are playing a game of scatter–and–entrench. Then, when they are ready to move, they begin first attacking a few worlds which were faithful to the Vorlons. By the time ‘Into the Fire’, episode 06, comes along, the Shadows and Vorlons are going at it direct, but only because they were lured there by the White Star fleet.
They do yet want the younger races to side with their beliefs: both the Shadows and the Vorlons only attack those who have already chosen the other side.

Now, what does Babylon 5 mean to either the Shadows or the Vorlons for those episodes of season four?

Babylon 5 did have a Vorlon ambassador for quite some time, but they themselves ousted him during ‘Falling Towards Apotheosis’.
The Vorlons also knew that the Shadows had been using ever since Kosh first encountered Morden there in the first season.
So, why didn't either of them take moves to eliminate Babylon 5 when they began cleansing the galaxy during season four?

It is possible that the Great Machine in Epsilon III served as a deterrent, but we never see any evidence that its defensive weapons were used against either the Shadows or the Vorlons. That may be simply because the situations were not dire enough so as to require the intervention. We certainly don't see evidence of it intervening when the Shadows took Garibaldi.
It is also possible that neither Shadows nor Vorlons knew of the Machine. This is unlikely, however, given at least the fact that Susan Ivanova seemingly alerted the Shadows of its presence, and her use of it, during ‘Voices of Authority’, season 3, episode 05. It isn't clear exactly what is occuring during that time, and whether she is traversing some transspacial network or simply probing the databanks of the Great Machine, but Ivanova does seem to believe that something noticed her.
It would seem reasonable to conclude that the Vorlons would've learned what it was too, but we can't be certain. Nevertheless, it also seems reasonable to surmise that the Great Machine, if it would've posed a threat to either the Vorlons or the Shadows, simply would've increased the necessary firepower from either for them to do defeat Babylon 5.

So, I would argue that the fact that neither Shadows nor Vorlons made a move on Babylon 5, prior to when Sheridan and Delenn prompted them to notice the fleet of Non-Aligned Worlds which had gathered in ‘Into the Fire’, signifies that it wasn't a priority target for either of them.
I know, that seems like circular reasoning. However, if Babylon 5 were a target for either of them, we'd expect that both the Shadows and the Vorlons would've made moves to meet there to prevent the other from taking it for their own. They did no such thing.

Furthermore, it doesn't seem like either the Shadows or the Vorlons regarded the humans of B5 as contenders for their own positions until Lorien asks them to follow him out beyond the rim. They were simply one of the younger races, albeit a rather vehement race. Both the Shadows and the Vorlons continued trying to win over the humans until the very end.
This occurs in episode 06, when we see the Vorlons as a woman encased in ice and the Shadows as doppelgängers. From then on, the Shadows and the Vorlons are gone away. They don't themselves meddle with Babylon 5 later.

Those are the reasons why neither the Shadows

nor the Vorlons

attacked the Babylon 5 station.

Answer 5

Put simply, they didn't see Babylon 5 as a threat.

Up until the battle shown in Shadow Dancing, Babylon 5 was attempting to marshal forces from every race but wasn't actively doing anything with them. The most they could be said to be doing to completely stop the Shadows was helping refugees get out of battlezones. The station in general was opposing the Shadows, sure, but until they stood up and bloodied the Shadows it wasn't any more important than any other force.

In addition, since Babylon 5 was a free port, they could slip agents in and out at any time. Morden practically had a permanent table in that restaurant, and the Centauri were still semi-allies with a strong presence there. They probably thought they could keep a strong eye on the "Army of Light" that way.

When the threat was made apparent, they were careful to figure out the situation. They pegged John Sheridan as the bigger threat, as the rallying force, and Babylon 5 as his "support mechanism". To be removed if he wouldn't work with them, as shown in Z'ha'dum, but not dangerous enough if he could be neutralized. He was, in a manner of speaking.

Once John's nuclear gambit played out, they had bigger Vorlon problems to worry about.

Answer 6

The shadows needed time to build their strength. Had they struck too early it would have brought the much-better-prepared Vorlons into the fight. There were in-universe discussions about this during many of the Delenn-G'kar conversations.