The series is Vampire Earth, but more accurately the books are military SF about an armed resistance to the alien occupation of America with everything from Dune’s worms to vampires thrown in along the way.
Fall with Honor isn’t as goofy as that summary makes it sound. E.E. Knight is a reasonable successor to S.M. Stirling. Like Stirling he does a good job of rooting an ongoing struggle in daily mundane affairs. Fall with Honor focuses on an attempt to link up with a resistance movement in West Virginia on a march that takes a regiment and Valentine’s rag tag band of pardoned Quisling collaborators through Kentucky to West Virginia. And like a few of the Vampire Earth books, things don’t go according to plan.
Knight is trying to move Valentine more naturally up the chain of command, giving him more command experience. The title tells the story well enough. Fall with Honor is about what happens when the plan doesn’t work and the fallback is to stand and fight or run away. It’s not an original story, but the book does a decent job of laying out the military realities. The Moondaggers are a little too exaggerated and the big battle is anticlimactic, but Fall with Honor is an improvement over Valentine’s Resolve.