Whenever I struggle to end things that culminate in some epic final battle sort of thing, I tend to give a brief summary of events, as well as give an overview of the aftermath of events, not only does it nicely tie everything up, as well as dealing with any loose ends in a somewhat satisfactory nature, it also gives the reader something to think about.
It's a great tool to use when a war or rebellion is the ultimate climax of a story, writing the aftermath and your character's involvement in it portrays the devastation that usually follows such events, not only that, but if you end it in a specific way, you can set yourself up for a sequel.
Here's one of my favourite examples that what I'm currently reading happens to use, it wraps up the last couple pages with an aftermath of a great, bloody, insanely visual and graphic battle against demons by telling you about survivors burying bodies of their fallen friends, comrades and family and then it closes with this.
"So many had to die, thought Alaric as he looked over the barren surface of Mimas, the huge, glowing disc of Saturn overhead. So many had to suffer. But sometimes, the fight was worth it, that's why the Grey Knights existed, the fight would never be over, but sometimes, it could be won."
Something like that, while a little cliché, does draw a nice, closing conclusion to a story, I was never good at endings, but I tend to find that doing that sort of thing helps you to bring about a satisfactory ending to whatever you've written, give it a go.