by John Ringo
Book 1 in the Posleen War series (2000)
With Earth in the path of the rapacious Posleen, the Galactic Federation offers help to the backward humans — for a price. You can protect yourself from your enemies, but God save you from your allies!
Humanity now has three worlds to defend.
As Earth’s armies rush into battle and special operations units scout alien worlds, the humans begin to learn a valuable lesson: you can protect yourself from your enemies, but may the Lord save you from your allies.