Ender's Game

Ender's Game, by Orson Scott Card
ISBN: 0312932081
Published by Tor, 1991

After the Earth was attacked by Formics (aka "the Buggers"), a global government was formed.  One branch ruled Earth-based affairs while another governed the situation in space.  The government's pet project, though, was Battle School, where kids were trained in the art of war.  Ideally, these kids would grow up to be military geniuses, ready to defeat the Formics for good when they attacked again.  Andrew Wiggin, called Ender, was one of these kids.  Ender's Game tells the story of his journey from Earth to Battle School, and his experience waging war against aliens.