In the space around Sol system, there is a big big multispecies alliance that calls itself the Galactic Federation, or Confederation depending on translation, that has been keeping us in the dark. They've known about human kind for... well, the Romans had minor, secret, contact with them, and they arent the earliest.
Anyway, the Federation has a problem - they've been at war for 200 years with a race known as the Posleen who have been invading a hell of a lot of Federation planets (so far populated by Indowy, who are the Galactic version of sweatshop workers except the fuckers use nanites, a form of telepathy, and goddamned magic materials fabrication techniques) on the rim, and eating the inhabitants before industrializing and strip mining the shit out of the worlds to launch the next generation of conquistadorial carnivores on their way.
Now, here is the thing - none of the Galactic races can fight. At all. Its why they've been getting assfucked and eaten alive for 200 years without a single minor victory. The only ones physically built for it go into a coma if they kill a sentient life form, the sweatshop guys are pacifistic sheep, etc. Here is where it gets sticky - remember how I said they surround Sol system? The reason they havent talked to us despite our living in their backyard is that, as omnivores, we scare the shit out of them. But, the Posleen are almost into the Galactic coreworlds (ie, worlds not inhabited mostly by indowy) and they need help or the rich planets are gonna get raped too along with the only help around (us) in about... five years. So in exchange for access to their technologies, the warning message, and promises of material support and bankrolling for defense, the nations of earth have to start designing the guns, armor, vehicles, and starships needed to fight as well as equipping expeditionary soldiers to help defend other star systems. The NATO countries, the old Warsaw pact countries, everyone who wants help and access... they start coughing up regiments.
and thats just the first chapter or two. The series itself revolves around the first human contact, weapons development and training, the expeditionary forces sent to defend already invaded worlds, the first "preliminary" invasion of earth, etc. The series is stalled at 4 "major" books by the author (he got a little burned out, has since moved on two The Empire of Man series and the Dragons series, both scifi, both fantastic.) and 2 sidestory books in the same universe by other authors working with Ringo. This is infantry warfare, and the End of the Fucking World.
