[quote=@TheUnknowable]
If FTL jammers are strictly short range, and don't block you from jumping through their field, then what's the point of them?  Are they just to keep the enemy from jumping away?[/quote] You can't really block something which only intersects with realspace when it reemerges.
And even if the jammer can extend to hyperspace and all the other dimensions and forms of FTL others use, it doesn't stop ships from choosing their route around the field and then appear behind the fleet.
You can have longer radius for FTL jammers but those are more costly.
Durandal's is basically was suggested by the text to be just about enough to cover the fleet.

[quote]And how are we supposed to counter a tactical FTL jump unless we also have tactical FTL?[/quote] By using your own damn sensors to predict them and take that little time before the enemy re-emerges to target them with pinpoint accuracy. The enemy will have effectively zero chance to evade thus you effectively turn the situation around.

[quote]Also, where does the attack occur?  Is it in a system or interstellar space?
[/quote]I already mentioned this in the battle intro.
It occur in interstellar space.
The neutral zone is a lightyears long section of empty space.
Except the minefield and FTL jammers near the FPA border (and likely for the Dominion border, too)
Then you have various military installations in FPA space.
This may happen close to an asteroid belt or something to give additional cover for them.