I can no longer afford to be who I was.

They say every warrior knows the turmoil of setting aside the person they were born and becoming the one circumstances demand. It is this way before every mission.

Stroke by patient stroke, the razor glides over my scalp, taking me back to the naked pate defining one who has set aside all but the struggle—and with it go the last vestiges of innocence. Tears flow in these moments, a psychological dance, a negotiation between nature and necessity. Paint comes next, red and black stripes, a grotesque chevron down my face, mirroring the savage paintjob of my strider, the machine awaiting me. When I am done I stare at someone I do not recognize, and am glad—I would not want to know this person.

It hardly matters anymore who was right. Those who knew the climate would fail or those who refused to credit the evidence when there was time. The camps became irreconcilable long before the end, and now war is just war. I can easily imagine that out there somewhere is a soldier much like me, who thinks and feels similarly, wants to live just as much, is just as dedicated to his or her cause—but believes in something else.

Earth has been uninhabitable ten years now. Those who survive the heat, the oxygen-poor air, howling grit-storms and thundering hurricanes, do so in sealed mega-structures that scrub the air, grow and synthesize food, are run by thorium or fusion piles, or use thermal energy imbalance to drive turbines. 95% of the human race has died since 2090, almost all other species are now extinct, stored away in gene banks, awaiting the time when “measures have been taken” to rebuild what we destroyed. Each year a batch of us from the city of Thunder Reach, beside an arm of the Great Lakes, leave for the sky, to newly-opened capacity at one of the L5 cities—Icarus, Prometheus, all sounding so grand, but we know they are just lifeboats for the human race, and, indirectly, every other species.

But we have just a little more destroying to do. Those who denied to the last that climate change was anthropogenic would now reach out and steal the resources of their neighbors, citing survival as the excuse for anything, and that’s where we come in. The weather keeps air travel to a minimum, and war is waged the old fashioned way.

We are city-states now. There’s no United States, no Canada, just cities, each with enough foresight to establish the tech to survive in the decade before final collapse. Thunder Reach has been skirmishing with the people of Mountain View, another pre-fab conurbation thrown up in the 2080s by Proconsul Industries as survival shelters. They overran their population and now raid us for their needs; and our cybernetic design and construction units turned out the striders to supplement the drones and ‘borgs that maintain our exclusion zone.

My unit is the Lakewalkers, a dozen striders, and we leave the hangar at 09.30, marching into the gray-brown gale that whips across the storm-churned face of Lake Superior. Sensors tell us an enemy unit, probably the Sasquatch Brigade, is circling a robot mining camp that crawls across the dead farmlands, harvesting still-useful organic molecules in the clay. Mountain View has as much need of them for their synthesis units as we, and less compunction—why build when you can take?

Because all bandits get what’s coming, and when we pick up the enemy striders a few miles on, via a secure link to the mine’s sensors, we fan out behind contour cover. Now we enter predator phase, blood pumps hot, and we forget our civilian lives. I’m keenly aware of the twin rotary canons on the forearms of this beast, the single-barrel 40mm unit over my shoulder, the mines, decoys, sensor packages and a dozen other systems I will use as needed. I’m good at what I do, and in the cool air of the towering machine the sensory helmet gives me total perception, as if I walk unclad through our inclement hell.

The enemy striders make their run, 15 colossi thundering out of the storm, and we break cover, canons presented. Red and green tracer lights the gloom and targets go down, stumble, roll, claw back to their feet, and in thirty seconds the battlefield becomes a toe to toe swinging match as we bound over a crest and go at them, canons and cudgels, mines and metal fists like hammers.

I take my target in a body tackle, my 3000 pounds swiping it from its feet, and I bludgeon the pilot capsule, three terrific blows as my foot pins a flailing arm, its canon hosing rounds. A seal smashes and the pilot has more to worry about than me. I look up, raise both fists and trigger my weapons point-blank, lifting another Sasquatch from its feet in a halo of detonations.

A titanic blow bowls me over, I claw to turn and see an enemy strider towering above me, a downed comrade held above its head, ready to smash down upon me. But an incoming heavy round takes it in its side and it goes over backward in stately slow-motion.

And suddenly the fight is done, a few Sasquatch withdraw, dragging damaged comrades, and I rise with a howl of servos. Only the wind buffets me now, and I check for survivors.

The irony? If I had died a moment ago they would have rewarded my memory with the Medal of Freedom; but the only reward for survival is to be sent back to do it again, and again, until I either qualify for relocation, or my life is over.

An old tradition says purgatory comes before heaven, and this is probably it. We are the damned souls, yet hoping for redemption, and the bitterest truth of all is that all hells are of our own making.