Skipping forward to work on the ending got me unstuck, and it's also going to save me some rewriting. The ending is basically a big battle, and when I skipped ahead I put myself in my protagonist's head and tried to figure out why he was fighting there. He's a wily, highly intelligent man; he's not going to allow himself to be trapped into a fight against overwhelming odds for no good reason. (And "because the plot needs a battle here" and "it makes for a cool historical parallel" don't qualify as good reasons!) Eventually I hashed out a reason that made sense, but one that completely changes the whole set-up of how and why they get to the place where the pivotal battle happens. I.e., the part I skipped past.
I also reached p. 400 on the manuscript about 20 minutes ago! Woohoo!
Last but not least, I got my PNWA feedback forms today. I knew they must be good or I wouldn't have finaled, but one of my judges just raved and gushed about the idea, and my writing, and all that wonderful ego-boosting stuff. The only negative thing s/he said was to very nicely point out that I really need to reveal the ending in my synopsis...but the thing is, I do reveal it. It's just that since this is the end of Book One, the ending is "Our heroes live to fight another day, although unbeknownst to them the help they're counting on will never arrive," as opposed to "Our heroes triumph and live happily ever after." I'd thought it would be obvious it's the first book in a series, and I'm sort of huffy and embarrassed that anyone would think I'm such a rank amateur as to not reveal my story's ending in the synopsis! So I guess I need some sort of line about how this is the first book of a proposed series or something to that effect.
But other than that, the judge said it was a great idea, and "so cool," with "a real cause, a real protagonist, super antagonists, wonderful game of 'what if?'"
And the other judge was nearly as complimentary, only suggesting that I try to get in a little more descriptive sensory detail. Which is totally one of my weak points and something I'm going to address on revision. But s/he praised my characterization, pacing, story hook, etc.
So, all in all, this is a good day.