The monumental Hugo and Nebula award-winning science fiction classic features a new introduction by John Scalzi. The Earth's leaders have drawn a line in the interstellar sand, despite the fact that the fierce alien enemy they oppose is inscrutable, unconquerable, and very far away. A reluctant conscript drafted into an elite military unit, Private William Mandella has been propelled through space and time to fight in a distant thousand-year conflict, performing his duties and doing whatever it takes to survive the ordeal and return home. But "home" may be even more terrifying than battle, because, thanks to the time dilation caused by space travel, Mandella is aging months while the Earth he left behind is aging centuries.