JERRY POURNELLE: THE MERCENARY

Orbit paperback, 1977. Cover artwork by Tony Roberts, thanks to all
who left comments identifying the artist!

Back cover fluff: 

"The Co-Dominium Navy . . . shipping prisoner colonists by the hundreds of thousands to strange worlds for a corrupt alliance of Earth nations. 

The Co-Dominium Marines . . . keeping uneasy peace on dozens of planets as their resources are robbed for the benefits of Earth. 

The Mercenaries . . . using their own methods to end the fighting as raging riots of independence explode into open warfare. 

And Falkenberg . . . a legend in his own time, a man who gave up a brilliant military career to fight on his own, a mastermind to his soldiers, an enigma to the politicians who buy his services - and the cause of turmoil on a dozen planets."