Ender's Game by Orson Scott Card
Six year old child-genius Ender Wiggin is drafted into Battle School to spend the next five years being moulded into Earth's ultimate military commander in order to defeat the insectoid Buggers in the forthcoming war.
A deserved winner of both the Hugo and Nebula awards for best novel in 1986, this is an expansion of the original novelette published in Analog magazine in 1977.
The way in which the author relates how the military proceed to break down and form Ender into the soldier they want him to become, resulted in the novel being used in courses taught at the US Marine University at Quantico.
In the introduction the author states that, as well as the military, the novel seems to resonate particularly with gifted children, who often feel excluded and can easily empathise with Ender — a point of view I can easily believe, as I found the story to be a real page-turner, with a lead character who grabbed my attention from the first chapter with the decisive way he dealt with a school bully.
A must-read book for any SF fan.