How did the Klingon war that Sisko refers to spread Starfleet thin?

Question

DS9 "In Purgatory's Shadow (Part 1)":

SISKO: A Dominion invasion of the Alpha Quadrant will affect Cardassia every bit as much as it's going to affect us. Besides, we need all the help we can get. The Dominion picked a perfect time to invade. The Cardassian fleet is in shambles, the Romulans are not much better off, and between the Klingon War and the recent Borg attack, Starfleet's spread pretty thin.

Starfleet never engaged in a battle with the Klingons at this point other than the attack on DS9. That attack DS9 held out and then Gowron stood down. The station made a full recovery from that attack a long time ago. Not a single Federation ship was involved in that altercation except for the Defiant which is in fine working condition by the time of this episode.

Were there other excursions or battles between Starfleet and the Klingons that could have spread the fleet thin?

Answer 1

The Borg are back...

After the Borg encounter in First Contact, Starfleet would almost certainly have reacted by sending out vessels to protect outer colonies, especially those close to the Borg cube's flight path. Even if Starfleet Command were to conclude that the Borg would probably not send another cube for some time (based on the time elapsed between "Best of Both Worlds" and First Contact), it would still be unwise not to beef up its presence out at the fringes.

There is a political element at work here, too. If you were living in an outer colony of the Federation and a Borg cube just passed within a few parsecs of your world, you can imagine the panic that might ensue around you, and that panic could easily last for months or longer. Your elected officials would likely press the Federation for greater protection. The Federation Council would likely respond by sending starships out to these areas.

Couple all of this with the fact that some starships were lost in the battle with the cube.

The Klingons are not to be trifled with...

By the time of TNG, the lengthy border between the Federation and the Klingon Empire no longer features the defence infrastructure it would have in the TOS era. After the Khitomer Conference of 2293, the Neutral Zone with the Klingon Empire was scrapped (leaving only the Romulan Neutral Zone), and as a gesture of peace, the starbases and defence installations along the former Klingon Neutral Zone were "mothballed" (to borrow Admiral Cartwright's wording from The Undiscovered Country).

All of sudden in DS9, the Federation finds itself at war with the Klingons again, after nearly a century. How will they defend the border? Almost certainly by sending an armada of ships to patrol the former Neutral Zone, in order to head off potential Klingon incursions and as a sign of strength.

Those sneaky Romulans...

The Romulans have a tendency to sit along the sidelines and take advantage of situations when the time is ripe. The Romulan Star Empire's two greatest foes are the Klingon Empire and the Federation — the Romulans would be pleased as punch that they are warring against each other once again. If past actions indicate anything, the Romulans might try to stir up further trouble. They might wish to ensure that the Klingon-Federation war is as long and bloody as possible, and could try to engineer incidents that would force one side to step up their offensive against the other (such duplicity on their part is certainly not unheard of and very much in the Romulan "style").

In any event, it would have been prudent for Starfleet to heighten its presence along the Romulan Neutral Zone. That means more ships diverted away from core areas of the Federation.

Conclusion

There are several good reasons why, at that particular time in DS9, Starfleet would be spread quite thin.

Answer 2

Spoiler alert.

What episode is the quotation from Sisko from?

I am assuming that the quote is from after the founders turned Odo into a solid and Odo remembered that Klingon chancellor Gowron was a changeling, just as Gowron sent an ultimatium to the Federation. That resulted in a war during much of the next season.

The war with the Klingons lasted for a number of episodes and there were many battles. There was one episode where Jake Sisco covered a battle as a reporter and found it was terrifying.

Eventually there was a shakey truce with on and off again fighting, but only the Dominion fleet coming through the wormhole and allying with Cardassia caused the Klingons to reaffirm the Khitomer accords and become friendly allies of the Federation again.

So the Klingon war did spread Starfleet a lot thinner than the op stated, unless the episode that quote is from was from between "Way of the Warrior" and the beginning of the Klingon war.

Answer 3

While there were no battles, there was still a potential for an attack. Because of that, you needed to delegate ships to patrol the long and wide border with the Klingon Empire, and have at least SOME kind of a fleet ready in case they attack.

That's a lot of ships doing a whole lot of nothing just in case Klingons attack.

And Klingons are just one of a few things spreading the Federation thin, others, you've listed yourself or asked about already.

Answer 4

There were a lot more engagements than just the attack on DS9. The following episodes (there may be others) mention or show engagements during the War.

Apocalypse Rising shows casualties from a Klingon ambush of the USS Drake and USS Armstrong.

Rules of Engagement deals with an event which occurred during a battle involving Klingon ships and the Defiant.

The Klingons also destroyed the USS Farragut in Nor the Battle to the Strong, while assaulting a Federation colony.

We have no reason to assume that these were the only fights either.