Some of our party rides out to meet battle, but not all. Merry, and others still healing, are left behind in Gondor. This journey is neither quick nor subtle, and that Sauron prepares a trap in wait is no surprise. Their presence is a clear and deliberate provocation of Sauron, and one that is nearly countered by the brief capture of Frodo. I think that if it were not for Gandalf the armies would have quailed, recognition by items that the Mouth of Sauron is referring to one of the hobbits. Of course, the key piece not mentioned in all of this is the Ring... and the fact that if Sauron had the Ring already the parlay would not even be necessary.
This chapter is definitely one that was ripe for translation to the screen. Cinematically it is both an apex and a cliffhanger, on top of the whole launching into likely doomed battle. Jackson made some pretty good decisions here to visually ramp up the tension. I can't really argue with the decision to have all of the Fellowship possible present, and there interactions are poignant as they face down their looming mortality and reflect in their friendship. I do wish that interactions with the Mouth of Sauron weren't cut (at least in the version I have, maybe it's in the Director's Cut since I know they did do the Mouth of Sauron), especially as I'm reminded yet again that Viggo's voice is not nearly resonant enough for my tastes.
Probably the best weaving here is something I don't want to talk about in full yet, but all along Jackson has been weaving the Books together, tying together chronology, and the splicing here is probably the best done of the trilogy as we go back and forth between battle and Sam & Frodo's final ascent.