"Are not, and were not the race that built the roads and made this machine," said Borden. "In fact, we've passed two forts where people like us died by tens of thousands, fighting against something from the white spot. They had long-range weapons, but at the end they were fighting with fire. You saw the soot! It was as if they burned oil by thousands of gallons to hold back something their long-range weapons couldn't stop. Fire is a short-range weapon, though a sun-mirror need not be. But nothing stopped this enemy. Vehicles like this were pulled right in half. That doesn't suggest people. It suggests a thing—something so gigantic and horribly strong that needle beams of flame couldn't stop it, and against which flame seemed a logical weapon to use. It must have been gigantic, because it could pull a land car apart endwise."
Ellen waited. Jerry knitted his brows.
"I'm afraid," Jerry said, "I can't think of anything that would be big and ... I just can't think what they could have been fighting."
"Think of what it wanted," Borden said drily. "It killed the population, wiped them out. Back on Earth, a long, long time ago, Ghenghis Khan led the Mongols to destroy Kharesmia. His soldiers looted the cities. They carried away all the wealth. They murdered the people. Plains were white with the skeletons of the folk they murdered. Do you notice a difference here?"
Jerry said irrelevantly, "You were right about the talkie, sir. Somebody's thrown it all out of tuning. I'll have to match it with the other to make use of it." Then he said painstakingly, "The difference between what you mentioned and the conquerors of the forts is that the loot was left in the forts. Engines and weapons and so on weren't bothered." Then he said in sudden surprise, "But the people weren't left as skeletons! They were all scattered!"
Jerry raised startled eyes from the talkie on which he was working. And suddenly he froze. Borden braked, stopped the car. They had come to a place where shattered ground cars were on the highway, on the sides of the road, everywhere. Here the road ran between monstrous steep-sided hills.
Borden started the car again and drove carefully around half of a vehicle which lay on the highway. Weapons had been mounted in it for shooting through the blister that was like the blister through which he looked in their car.
"There was a battle here, too," he said. "They fought with cars here. Maybe a delaying action to gain time to build the fort we just left. There are bones in these cars, too."
"But what were they fighting, Dee?" Ellen demanded again, uneasily.