The Mammoth Book of SF Wars by Ian Watson [Ed], Ian Whates [Ed] Page A

self-refit.
    Landing, she had immediately put out surface parties and air patrols – there were turret-mounted weapons all along her flanks; she was clearly a warship of some kind – in a display of resources that badly upset the Terrestrial military forces observing her. The surface parties were squat-profiled, tracked, armoured amphibious machines with sixteen-foot bogeys and a track-to-turtledeck height of seventy-five feet. They had fanned out over the surrounding states and, without regard to road, river, fence or farmhouse, had foraged for minerals. It had finally been concluded that the vehicles, equipped with power shovels, claws, drills, ore buckets and whatever other mining tools were necessary, were remote-controlled from the ship on the basis of local topography but not with any reference to the works of Man. Or to the presence of Man. The undeviating tracks made as much of a hayrick as they did of a company of anti-tank infantry or a battalion of what the Army in those days was pleased to call “armour”.
    Whatever had hurt her, there was no point in Earthmen speculating on it. No missile could reach her. She had antimissile missiles and barrage patterns that, in operation, had made the Mississippi plain uninhabitable. An attempt was made to strike her foraging parties, with some immediate success. She then extended her air cover to the entire civilized world, and began methodically smashing down every military installation and every industrial complex capable of supporting one.
    It was a tribute to the energy and perseverance of Twentieth Century Man. And it was the cause of Twenty-First Century man’s finding himself broken into isolated enclaves, almost all of them either underground or so geographically remote as to be valueless, and each also nearly incapable of physical communication with any other.
    It did not take a great deal of Terrestrial surface activity to attract one of the ship’s nearly invulnerable aircraft. Runner’s journey between Salt Lake and the tunnel pit head had been long, complicated by the need to establish no beaten path, and anxious. Only the broken terrain, full of hiding places, had made it possible at all.
    But the balance between birth and death rates was once more favourable, and things were no longer going all the ship’s way – whether the ship knew it or not. Still, it would be another thirty years before this siege bore Compton was driving could reach, undermine and finally topple the ship.
    Thirty years from now, Runner and the other members of Special Division knew, the biped, spindling, red-eyed creatures emerging from the ground to loot that broken ship and repay themselves for this nightmare campaign would be only externally human – some of them. Some would be far less. Special Division’s hope – its prospects were not good enough to call it a task – was to attempt to shorten that time while Humanity was still human.
    And if the human race did not topple the ship, or if the ship completed its refit and left before they could reach it, then all this fifty years of incalculable material and psychic expenditure was irretrievably lost. Humanity would be bankrupt. They were all living now on the physical and emotional credit embodied in that tower of alien resources. From it, they could strip a technology to make the world new again – nothing less could accomplish that; in its conquest, there was a triumph to renew the most exhausted heart. Or almost any such heart. Runner could only speculate on how many of the victors would be, like Compton, unable to dance upon the broken corpse.
    If anyone on Earth doubted, no one dared to dwell aloud on the enfeebling thought.
    They had to have the ship.
    “She’s got some kind of force field running over her structure,” Compton remarked, looking at the image on the screen. “We know that much. Something that keeps the crystals in her metal from deforming and sliding. She’d collapse. If we had something like that