The Forever War is a military science fiction novel written by Joe Haldeman and published by St. Martin’s Press in 1974. It was followed by the sequels Forever Peace (1997) and Forever Free (1999) and A Separate War (1999), but it works as a standalone book (presumably having been sold and published as one).
The protagonist of the story is William Mandella, a soldier in an interstellar war against an alien adversary (known as the Taurans) that no one understands. Even though humanity now has the technology to travel through wormholes for quicker interstellar travel, travel is still very slow from a bystanders point of view, and because of time dilation at very fast speeds, relatively fast for the travelers. This has major implications for the length of the war as well as the way an arms race will play out, because when your ship and a Tauran ship make contact their technology could be hundreds of years more or less advanced than yours depending on the planet of origin and time of departure. Mandella, through several long tours, experiences a much longer stretch of the war than most of his fellow soldiers, taking some civilian time in between.
I thought the novel did very well at the military SF part of the story, using the alien conflict as a metaphor for our wars, in the hopelessness and separation and desperation of soldiers, doing whatever they can to survive their tour. This was magnified by the complications of space travel and fighting an alien when you don’t know their technology or language or anatomy. Haldeman wrote the novel after serving as a soldier in Vietnam, and his experience shows through in the feel of the story, it feels very real.
The civilian and some of the interpersonal parts of the story even during the military sections, I found much harder to get into. I don’t know if this is a consequence of shifting general views in the 44 years since the book was published, but whenever he was going through a civilian part of his life, I was ready for that part to end–in particular the character’s views on homosexuality as the culture around him grew more and more to accept homosexuality as the norm. (The character didn’t strike me as homophobic, exactly, but it sometimes seemed like that was all he could see about the people around him)
Overall I thought it was good military SF, lots of actions and strategy, though frustrating at times.