The Light Brigade by Kameron Hurley

The Light Brigade : it's what soldiers fighting the war against Mars call the ones who come back...different. Grunts in the corporate corps get broken into light, travelling from interplanetary battlefronts. Everyone is changed by what the corps must do. Those who survive learn to stick to the mission brief - no matter what happens during combat.

Dietz, a fresh recruit in the infantry, begins to experience combat drops which don't sync up with the platoon's. And the bad drops tell a story of war that's not what the corporate brass want the soldiers to think it is. Is Dietz really experiencing the war differently, or is it combat madness?

Trying to survive with sanity intact, Dietz is ready to become a hero - or maybe even a villain. In war it's hard to tell the difference.