But this is an introduction to a volume of Hammer's Slammers stories, and so I'd like to mention a few things that might not be immediately obvious. Certainly Drake uses both his detailed knowledge of military history and his own experiences and observation from his service in Vietnam to construct what is probably the most authentic military SF fiction of this era. But it appears to me that he is often doing a great deal more and that his fiction can yield up some surprising additional benefits.
For instance,his early story,"Ranks of Bronze,"and the later novel of that title, adapts a real historical event(a lost legion of Roman soldiers,Crassus' mercenaries—see Drake's afterword to the novel) and translates it into SF. A Roman legion is snatched from Earth into space to be used as mercenaries owned and operated by superior aliens out for profit, to fight relatively low-cost, low-technology wars on alien planets against alien races, with whom they have no personal quarrel, and perhaps only dimly comprehend. No one in the legion has any choice in this. The soldiers behave in a convincingly plausible way, the way Roman soldiers would. They are a very effective fighting force and can most often win. They are moved without notice from one planet to another, fight (sometimes die). They are wretched.
This is military SF with the contemporary politics stripped off, and removed from the level of policy decisions. The soldiers go to a place. They are told who to fight. They win or die.