I was trying to word the question so the title is not a spoiler, but also so it was not too vague. I am assuming that any person concerned with spoilers would stop reading at this point.
In Deep Space 9 S3E21, the Romulan/Cardassian fleet realize they have been tricked when 150 Jem'Hadar ships appear from a nearby nebula. Their 20 ships are vastly outnumbered and they are annihilated in battle. Why didn't the Romulans re-cloak and leave? They stated earlier in the episode that the Jem'Hadar cannot detect them as long as they keep their warp speed low. They had plenty of time to cloak and leave before the Jem'Hadar ships arrived from the nebula, so why did they sit still and allow themselves to be destroyed?