In Her Name First Contact by Michael R. Hicks
I got the Kindle version for free. It is still free. The paper back version is $10.95 at this time.
If you are into space, ships and combat both in space and on the ground then you need to add this to your collection. I have read it a couple of times and would highly recommend it. I like how it is written and the book flows well. It is told well enough that it pulls you in universe and leaving you wanting more. Oh and there are more to read to keep you in universe.