This is the best Sci-fi books I had read in a long time, and one of the best ever. An allegory for the Vietnam war, or indeed, war of any kind.
The Earth’s leaders have declared a war against the Taurans, a fierce alien enemy. Never mind that said enemy is inscrutable, unconquerable, and very far away. William Mandella has been drafted as one of the first troops that will be sent to fight the Taurans. Ostensibly, the war is being waged to control collapsars - wormholes that will transport a ship to a distant area in the universe instantly. Both races like to build bases on nearby planets to establish control of the area around the collapsars.
Unfortunately, most planets are usually cold lifeless rocks, and just training to use their suits in these environments is dangerous, let alone trying to fight an alien race they know little about. Mandella gets through training and manages to survive the first battle with the Taurans. That’s where the book gets really interesting.
While the collapsars provide instant space travel, the ships still have to get to the nearest one and that means months of travel at near light-speed. So while the troops on the ship feel like a journey only took months, relativistic time dilation causes years to have passed for everyone else. When Mandella returns to Earth after his first battle, he’s only aged two years, but ten years have passed on Earth.
Since Mandella has to do more and more light speed journeys, centuries pass on Earth even though it’s only been a few years for him. Mandella will return from missions to find that humanity has changed so much that he has almost nothing in common with the rest of the people, and since he manages to survive several campaigns when almost everyone else dies, he’s quickly becoming one of the oldest men in the universe during his ten year (subjective) enlistment.
Another quirk of the time differences is that when the humans meet the Taurans, they can’t know if they’re battling alien troops who are centuries ahead or behind them in terms of military intelligence and weapons technology. So Mandella and his fellow soldiers may have a huge advantage or be severely outgunned. It just depends on if the Taurans they’re fighting started their light-speed journeys before or after they did.
As the war drags on for century after century, it is both sustaining and draining Earth’s economy. Mandella finds himself losing all his family, his friends and his lovers to war or age. He is increasingly out of touch with Earth and the rest of humanity. The army continues to promote him, mainly because his seniority has reached ridiculous levels after centuries of service.
One of the things that isolates Mandella is that homosexuality becomes the norm due to Earth overpopulation. In an ironic reversal of don’t ask-don’t tell, Mandella is the outcast that disgusts many of his fellow soldiers due to his unenlightened ways. Even the slang spoken by other soldiers becomes incomprehensible to him. Increasingly lonely and out of sync with everyone around him with almost no chance of surviving his enlistment, Mandella nurses the hope that the war will someday end during the large gaps of time he skips as he travels to his assignments.
Absolutely enthralling read, I was not able to put the book down. Strongly recommend even if you are not a sci-fi fan.