The Forever War Series by Joe Haldeman

The Earth's leaders have drawn a line in the interstellar sand—despite the fact that the fierce alien enemy that they would 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 the distant thousand-year conflict; to perform his duties without rancor and even rise up through military ranks. Pvt... moreThe Earth's leaders have drawn a line in the interstellar sand—despite the fact that the fierce alien enemy that they would 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 the distant thousand-year conflict; to perform his duties without rancor and even rise up through military ranks. Pvt. Mandella is willing to do 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. less

2043 A.D.: The Ngumi War rages. A burned-out soldier and his scientist lover discover a secret that could put the universe back to square one. And it is not terrifying. It is tempting...

Together in one volume for the first time ever; his classic novel of epic future conflict, The Forever War, its sequel Forever Free, and the companion novel, Forever Peace.WARWilliam Mandella is a reluctant hero, drafted to fight in a distant interstellar war against unknowable and unconquerable aliens. But his greatest test will come when he returns to Earth... moreTogether in one volume for the first time ever; his classic novel of epic future conflict, The Forever War, its sequel Forever Free, and the companion novel, Forever Peace.WARWilliam Mandella is a reluctant hero, drafted to fight in a distant interstellar war against unknowable and unconquerable aliens. But his greatest test will come when he returns to Earth. Relativity means that everey time he returns home after a few months' tour of duty, centuries have passed on Earth, making him and his fellows ever more isolated from the world for whose future they are fighting.FREEWhen Mandella returns for the last time he finds humanity has evolved into a group mind called Man. Living a dull life in an autocratic and intrusive society, missing the certainties of combat and feeling increasingly alienated, the veterans plan an escape. But when their ship starts to fail, their journey becomes a search for the unknown.PEACE2043. The Ngumi War rages, fought by 'soldierboys', indestructible machines operated remotely by soldiers hundreds of miles away. Julian Class is one of those soldiers, and for him war is truly hell. But he and his companion, Dr Amelia Harding, have discovered something that could literally take the universe back to square one. For Julian, the discovery isn't so much terrifying as tempting... less

William Mandela is a genetic throwback, one of the small group of humans who fought and survived the Forever War. They returned to find humanity has evolved into a group mind called Man. Surrounded by a society that is too autocratic and intrusive, living a dull existence which cannot compare to the certainties of combat and feeling increasingly alienated, the veterans plan an escape to the future by means of space travel and relativity... moreWilliam Mandela is a genetic throwback, one of the small group of humans who fought and survived the Forever War. They returned to find humanity has evolved into a group mind called Man. Surrounded by a society that is too autocratic and intrusive, living a dull existence which cannot compare to the certainties of combat and feeling increasingly alienated, the veterans plan an escape to the future by means of space travel and relativity. But when their ship starts to fail, their journey becomes a search for the Unknown, the elusive entity responsible. less