Books like The Forever War

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. 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.

Liked The Forever War by Joe Haldeman? Here's what readers who loved it picked up next.

Old Man's War by John Scalzi (2005) · 4.23★
Starship Troopers by Robert A. Heinlein (1959) · 3.99★
Ringworld by Larry Niven (1970) · 3.96★
A Fire Upon the Deep by Vernor Vinge (1992) · 4.13★
Hyperion by Dan Simmons (1989) · 4.21★
Armor by John Steakley (1984) · 4.12★
The Mote in God's Eye by Larry Niven (1974) · 4.06★
Gateway by Frederik Pohl (1977) · 4.07★
Rendezvous with Rama by Arthur C. Clarke (1973) · 4.06★
The Stars My Destination by Alfred Bester (1955) · 4.13★
The Moon is a Harsh Mistress by Robert A. Heinlein (1966) · 4.17★
Revelation Space by Alastair Reynolds (2000) · 3.97★