Man-Eater. Murphy's Lawless, #3

Taken from their planet and their century, they are.the Lost Soldiers. Some of the hijacked Twentieth Century troops known as the Lost Soldiers have made planetfall on the planet R'Bak and accomplished their first main objective: capturing much-needed combat vehicles. Now reinforced by the nomadic locals, this rump company-known as Murphy's Lawless-are moving to prevent the local J'Stull aristocrats from calling their off-world overlords to take care of the "unidentified invaders." The J'Stull plan: use spies and call in favors to find the vehicles and camp from which the "Terran" invaders plan to mount their offensive.
The only countermove that Murphy's Lawless can make in time is to identify-and eliminate-the spies. Fortunately, orbital SIGINT has intercepted a radio transmission from a J'Stull agent near the village of Clarthu, and it's up to Warrant Officer Horace Chalmers-a disgraced Criminal Investigation Division officer-and his partner Sergeant Jackson to find and eliminate the spy. With extreme prejudice. But Chalmers is trying to achieve yet another goal on this operation: redemption.
To start being a better human than the one who got shot down in a helicopter off Mogadishu on his way to Fort Leavenworth: a dirty cop whose misdeeds guaranteed that his partner Jackson would be on that chopper, too-and so lose everything and everyone he ever loved.  But Chalmers has never been very good at turning over a new leaf, and he knows nothing of the indigenous tribes. To make matters worse, there's no room for failure; Murphy's Lawless are already on the move.
Their attack force will soon roll past Clarthu and be reported-and targeted-by the spy there. If Chalmers and Jackson can't identify and eliminate that menace, the convoy will not only be prevented from completing its mission, but might be wiped out entirely. And with it, every other time-stranded soldier in Murphy's Lawless.