The Forever War is a Vietnam War novel set in space, although Haldeman accepts that most of today's readers won't make the connection. Regardless of its historical context, the novel stands independently as one of the finest polemical works in science fiction. Through relentless extrapolation of a single science-fictional idea, Haldeman illustrates the grand futility of warfare, the often random chains of events that lead to unthinkable costs (in both financial and human terms).
Opening in what was, at the time of 'Nam, the near future -- the late 1990s -- the novel has now become a kind of alternative-future history, but it loses little with the passage of time. At first, the story appears to be straight military sf: after discovery of the 'collapsar jump' has made long-distance space travel possible, a colony ship is apparently destroyed by hostile aliens and the Forever War of the title begins. Space exploration immediately becomes a military endeavour, with elite conscripts staking out territory on planets orbiting the collapsars, looking for confrontation with the enemy. Pretty soon, our protagonist, Private William Mandella, is in the thick of the action, a reluctant warrior who just happens to have a knack for survival.
And then, the big idea kicks in: all that travelling at near the speed of light means that relativistic time dilation carries the soldiers into the future. Every interstellar journey takes the soldiers into a future where the aliens might have had time to develop vastly superior technologies. Every time the soldiers get some R&R they encounter a human society transformed from the one they had known: the equivalent of neolithic hominids thrown into the 20th century.
And yes, as Peter Hamilton says, the book is near perfect, suffering only a little from the passage of time, and a little more from a sparseness of characterisation that may have been intentional but at times has a distancing effect between protagonist and reader.
This reissue of The Forever War fills what had been a gap in my reading, just as the SF Masterworks series will do for many in my generation. The series is well chosen and the books beautifully produced, and I have a shelf set aside for them already.
http://www.infinityplus.co.uk/nonfiction/forever.htm
