I followed up my recent re-read of Heinlein's Starship Troopers by re-reading Joe Haldeman's The Forever War (my copy was signed by Joe way back in 1980, when I first met him... we must both have been so young back then...).
Haldeman's book is often seen as an answer to, or critique of, Heinlein's - and there's some truth in that. But it also owes much to Heinlein's, with similar narrative structures and techniques on display.
The Forever War compellingly depicts the harshness of military training and the sheer terror, danger, and suffering of armed combat; but to be fair to Heinlein, Starship Troopers does not deny or downplay any of these things. They are always present, and even emphasised, yet they are painted with an overlay of anti-glamorous glamour. By that, I mean that there is no glamour in the daily discipline and tasks of a working soldier, as presented by Heinlein - it's all acknowledged as difficult, tedious, demanding, and dangerous - but there's a kind of allure or mystique created around being the sort of person who will step up and embrace this as a form of social responsibility. Haldeman, by contrast, removes even that kind of attraction from his portrayal of military life and all that it involves.
Like Starship Troopers, The Forever War is told in the first person by a narrator who has obviously survived the experiences he describes to us. In each case, the narrative depicts the military career of an individual soldier as he advances through the ranks. There is, perhaps, a grittier feel to Haldeman's prose: more focus on the grim details of training, work, and combat, as if we were there ourselves, with less reflection on the experience from the narrator's current perspective. When, however, that reflection is offered, it comes from a voice that sounds far more bleak and cynical than that of Heinlein's narrator, Juan ("Johnnie") Rico.
By contrast with Rico, Haldeman's William Mandella never comes to appreciate the essential benevolence and wisdom - or the necessity - of the military forces in which he serves. There's no sign of any of this - at most, we can say that some individual officers are personally impressive, and that Mandella encounters some of the difficulties of active command in a war zone. If Starship Troopers can be read as recruitment propaganda, The Forever War is fairly much the opposite.
Most shockingly, however, the eponymous war does not actually last forever (unlike the war against the Bugs in Starship Troopers, it has an ending that is revealed in the book). The shocking part is that the war turns out to have been completely unnecessary, based on a misunderstanding for which human beings, and especially human military leaders, have been mainly responsible. The dreaded and (to humans) visually disgusting enemy - the Taurans - have been the relatively innocent party throughout, while we have been the aggressors from the start.
Whereas Heinlein takes war to be inevitable and beyond moral criticism - its inevitability is an amoral feature of the background against which moral judgments are made - Haldeman presents war not only as Hell (Heinlein also does this, and with almost as much literary force) but as an unnecessary, futile, absurd sort of Hell. Whereas Heinlein depicts high-level military commanders as essentially wise and benevolent, Haldeman depicts them as utterly ruthless in their exploitation of the men and women who serve under them.
Leaving aside its obvious critique of war and the military, The Forever War contains much in the way of social and moral commentary as it depicts the varied mores of several periods in future human history. Because Mandella spends much of his military service in space vessels travelling at relativistic velocities, he effectively keeps time-travelling into the future. That is, in fact, one reason why he renews his military service: there is no place for him in the radically changed human society that he encounters the first time he returns to Earth from a battle with the Taurans. But it also gives Haldeman the opportunity to comment slyly on sexual mores and varied conceptions of freedom.
Perhaps strangely, Haldeman provides a happy ending in a way that Heinlein does not. The war is eventually resolved amicably and abandoned by both sides, and Mandella finally discovers a path out of military service, along with his lover, Marygay Porter. If we don't buy Heinlein's line about the necessity of war, we may actually see the narrative arc of his novel as more pessimistic than that of Haldeman's. (Conversely, the ending of The Forever War feels, to an extent, like a cop-out, given all that we have seen to that point; whatever its weaknesses, and however much its political philosophy might seem untenable or infuriating, no one could make that particular criticism of Starship Troopers.)
Over the past forty years or more, Haldeman has been one of the most respected SF writers among his peers, while also establishing a large fan base. The Forever War shows why he's so admired and popular. He was - and is - a superb exponent of the craft of fiction writing. His portrayals of futuristic equipment and military tactics are especially vivid and convincing. There's always a sense with Haldeman that he's the real deal: as a talented and capable author, and as someone who knows what he's writing about.