(by Robert N. Charrette): Often cited as one of the best standalone novels in the entire series, detailing the relationship between Wolf's Dragoons and the Draconis Combine.
The first novel published was The Sword and the Dagger (Armin Shimerman, 1987). It is out of print, poorly written, and its events are largely retconned. The second was Decision at Thunder Rift (William H. Keith, 1988) – which is excellent, but it is a prequel about a tiny mercenary unit (the Gray Death Legion) that has almost no bearing on the galactic civil war.