Man may some day outgrow his interest In war, but don’t hold your breath. The combative urge was such a strong factor in scaling the evolutionary ladder that it cannot be easily put aside; and while the idea of war may terrify us and disgust us, the prehistoric bodies we wear still react enthusiastically when the drums roil and the cannons rumble by. As witness our present situation-we watch with fascinated interest as all sorts of ingenious and dedicated people work up the weapons that can, if That Button ever gets pushed, wipe us all from this planet.

Should this not happen, man will very likely cheerfully export his wars to the rest of the galaxy. If the alien races encountered are not warlike enough to fight back .

too bad for them. And if there aren’t enough aliens around to fight, man will just have to fight his oldest enemy. Himself. Of course, his companions, the robots, will fight as well. And it’s all too clear that in some ways a robot would be a perfect soldier-less destructible, more efficient at destruction… and, of course, you can build in the killer-instinct…

Harry Harrison - SURVIVAL PLANET

“BUT THIS WAR WAS FINISHED years before I was born! How can one robot torpedo - fired that long ago - still be of any interest?”

Dall the Younger was overly persistent - it was extremely lucky for him that Ship-Commander Lian Stane, both by temperament and experience, had a tremendous reserve of patience.

“It has been fifty years since the Greater Slavocracy was defeated - but that doesn’t mean eliminated,” Commander Stane said. He looked through the viewport of the ship, seeing ghostlike against the stars the pattern of the empire they had fought so long to destroy. “The Slavocracy expanded unchecked for over a thousand years. Its military defeat didn’t finish it, just made the separate worlds accessible to us. We are still in the middle of that reconstruction, guiding them away from a slave economy.

“That I know all about,” Dall the Younger broke in with a weary sigh. “I’ve been working on the planets since I came into the force. But what has that got to do with the Mosaic torpedo that we’re tracking? There must have been a billion of them made and fired during the war. How can a single one be of interest this much later?”

“If you had read the tech reports,” Stane said, pointing to the thumb-thick folder on the chart table, “you would know all about it.” This advice was the closest the Commander had ever come to censure. Dall the Younger had the good grace to flush slightly and listen with applied attention.

“The Mosaic torpedo is a weapon of space war, in reality a robot-controlled spaceship. Once directed it seeks out its target, defends itself if necessary, then destroys itself and the ship it has been launched against by starting the uncontrollable cycle of binding-energy breakdown.”

I never realized that they were robot-operated,” Dall said. “I thought robots had an ingrained resistance to killing people?”

“In-built rather than ingrained would be more accurate,” Stane said judiciously. “Robotic brains are just highly developed machines with no inherent moral sense. That is added afterwards. It has been a long time since we built man-shaped robots with human-type brains. This is the age of the specialist, and robots can specialize far better than men ever could. The Mosaic torpedo brains have no moral sense - if anything they are psychotic, overwhelmed by a death wish. Though there are, of course, controls on how much they can kill. All the torpedoes ever used by either side had mass detectors to defuse them when they approached any object with planetary mass, since the reaction started by a torpedo could just as easily destroy a world as a ship. You can understand our interest when in the last months of the war, we picked up a torpedo fused only to detonate a planet. All the data from its brain was filed and recently interpreted. The torpedo was aimed at the fourth planet of the star we are approaching now.”

“Anything on the record about this planet?” Dall asked. “Nothing. It is an unexplored system-at least as far as our records are concerned. But the Greater Slavocracy knew enough about this planet to want to destroy it. We are here to find out why.”

Dall the Younger furrowed his brow, chewing at the idea. “Is that the only reason?” he finally asked. “Since we stopped them from wiping out this planet, that would be the end of it, I should think.”

“It’s thinking like that that shows why you are the low-ranker on this ship,” Gunner Arnild snapped as he came in. Arnild had managed to grow old in a very short-lived service, losing in the process, his patience for everything except his computers and guns. “Shall I suggest some of the possibilities that have occurred even to me? Firstly - any enemy of the Slavocracy could be a friend of ours. Or conversely, there may be an enemy here that threatens the entire human race, and we may need to set off a Mosaic ourselves to finish the job the Slavers started. Then again, the Slavers may have had something here - like a research center - that they would rather have destroyed than let us see. Wouldn’t you say that any one of these would make the planet worth investigating?”

“We shall be in the atmosphere within twenty hours,” Dall said as he vanished through the lower hatch. “I have to check the lubrication on the drive gears.

“You’re too easy on the kid,” Gunner Arnild said, staring moodily at the approaching star, already dimmed by the forward filters.

“And you’re too hard,” Stane told him. “So I guess it evens out. You forget he never fought the Slavers.”

Skimming the outer edges of the atmosphese of the fourth planet, the scout ship hurled itself through the measured length of a helical orbit,, then fled back into the safety of space while the ship’s robot brain digested and made copies of the camera and detector instrument recordings. The duplicates were stored in a message torp, and only when the torp had started hack to base did Commander Stane bother personally to examine the results of their survey.

“We’re dispensable now,” he said, relaxing. “So the best thing we can do is to drop down and see what we can stir up.” Arnild grunted agreement, his index fingers unconciously pressing invisible triggers. They leaned over the graphs and photographs spread out on the table. Dall peered between their shoulders and flipped through the photographs they tossed aside. He was first to speak.

“Nothing much there, really. Plenty of water, a big island continent - and not much else.”

“Nothing else is detectable,” Stane added, ticking off the graphs one by one. “No detectable radiation, no large masses of metal either above or below ground, no stored energy. No reason for us to be here.”

“But we are,” Arnild growled testily. “So let’s touch down and find out more first hand. Here’s a good spot,” he tapped a photograph, then pushed it into the enlarger. “Could be a primitive hut city, people walking around, smoke.”

“Those could be sheep in the fields,” Dall broke in eagerly. “And boats pulled up on the shore. We’ll find out something there.”

“I’m sure we will,” Commander Stane said. “Strap in for landing.”

Lightly and soundlessly the ship fell out of the sky, curving in a gentle arc that terminated at the edge of a grove of tall trees, on a hill above the city. The motors whined to a stop and the ship was silent.

“Report positive on the atmosphere,” Dall said, checking off the analyzer dials.

“Stay at the guns, Arnild,” Commander Stane said. “Keep us covered, but don’t shoot unless I tell you to.”

“Or unless you’re dead,” Arnild said with complete lack of emotion.

“Or unless I’m dead,” Stane answered him, in the same toneless voice. “In which case you will assume command.”

He and Dall buckled on planet kits, cycled through the lock and sealed it behind them. The air was soft and pleasantly warm, filled with the freshness of growing plants.

“Really smells good after that canned stuff,” Dall said. “You have a great capacity for stating the obvious.” Arnild’s voice rasped even more than usual when heard through the bone conductor phones. “Can you see what’s going on in the village?”

Dall fumbled his binoculars out. Commander Stane had been using his since they left the ship. “Nothing moving,” Stane said. “Send an Eye down there.”

The Eye whooshed away from the ship and they could follow its slow swing through the village below. There were about a hundred huts, simple pole-and-thatch affairs, and the Eye carefully investigated every one.

“No one there,” Arnild said, as he watched the monitor screen. “The animals are gone too, the ones from the aerial pic.”

“The people can’t have vanished,” Dall said. “There are empty fields in every direction, completely without cover. And I can see smoke from their fires.”

“The smoke’s there, the people aren’t,” Arnild said testily. “Walk down and look for yourself.”

The Eye lifted up from the village and drifted back towards the ship. It swung around the trees and came to a sudden stop in mid-air.

“Hold it!” Arnild’s voice snapped in their ears. “The huts are empty. But there’s someone m the tree you’re standing next to. About ten metres over your heads!”

Both men controlled a natural reaction to look up. They moved out a bit, where they would be safe from anything dropped from above.

“Far enough,” Arnild said. “I’m shifting the Eye for a better look.” They could hear the faint drone of the Eye’s motors as it changed position.

“It’s a girl. Wearing some kind of fur outfit. No weapons that I can see, but some kind of a pouch hanging from her waist. She’s just clutching onto the tree with her eyes closed. Looks like she’s afraid of falling.”

The men on the ground could see her dimly now, a huddled shape against the straight trunk.

“Don’t bring the Eye any closer,” Commander Stane said.

“But turn the speaker on. Hook my phone into the circuit.”

“You’re plugged in.”

“We are friends… Come down… We will not hurt you.” The words boomed down from the floating speaker above their heads.

“She heard it, but maybe she can’t understand Esperanto,” Arnild said. “She just hugged the tree harder while you were talking.”

Commander Stane had had a good command of Slaver during the war, he groped in his memory for the words, doing a quick translation. He repeated the same phrase, only this time in the tongue of their defeated enemies.

“That did something, Commander,” Arnild reported. “She jumped so hard she almost fell off. Then scooted up a couple of branches higher before she grabbed on again.”

“Let me get her down, sir,” Dall asked. “I’ll take some rope and climb up after her. It’s the only way. Like getting a cat out of a tree.”

Stane pushed the thought around. “It looks like the best answer,” he finally said. “Get the light-weight 200-metre line and the climbing irons out of the ship. Don’t take too long, it’ll be getting dark soon.”

The irons chunked into the wood and Dall climbed carefully up to the lower limbs. Above him the girl stirred and he had a quick glimpse of the white patch of her face as she looked down at him. He started climbing again until Arnild’s voice snapped at him.

“Hold it! She’s climbing higher. Staying above you.”

“What’ll I do, Commander?” Dall asked, settling himself in the fork of one of the big branches. He felt exhilarated by the climb, his skin tingling slightly with sweat. He mapped open his collar and breathed deeply.

“Keep going. She can’t climb any higher than the top of the tree.”

The climbing was easier now, the branches smaller and closer together. He went slowly so as not to frighten the girl into a misstep. The ground was out of sight, far below. They were alone in their own world of leaves and swaying boughs, the silver tube of the hovering Eye the only reminder of the watchers from the ship. Dall stopped to tie a loop in the end of the rope, doing it carefully so the knot would hold. For the first time since they had started on this mission he felt as if he was doing a full part. The two old warhorses weren’t bad shipmates, but they oppressed him with the years of their experience. But this was something he could do best and he whistled softly through his teeth with the thought.

It would have been possible for the girl to have climbed higher, the branches could have held her weight. But for some reason she had retreated out along a branch. Another, close to it, made a perfect handhold, and he shuffled slowly after her.

“No reason to be afraid,” he said cheerfully, and smiled. “Just want to get you down safely and back to your friends. Why don’t you grab onto this rope?”

The girl just shuddered and backed away. She was young and good to look at, dressed only in a short, fur kilt. Her hair was long, but had been combed and caught back of her head with a thong. The only thing that appeared alien about her was her fear. As he came closer he could see she was drenched with it. Her legs and arms shook with a steady vibration. Her teeth were clamped into her whitened lips and a thin trickle of blood reached to her chin. He hadn’t thought it possible that human eyes could have stared so widely, or have been so filled with desperation.

“You don’t have to be afraid,” he repeated, stopping just out of reach. The branch was thin and springy. If he tried to grab her they might both be bounced off it. He didn’t want any accidents to happen now. Slowly puffing the rope from the coil, Dall tied it about his waist, then made a loop around the next branch. Out of the corner of his eye he saw the girl stir and look around wildly.

“Friends!” he said, trying to calm her. He translated it into Slaver, she had seemed to understand that before. “Noi’r venn!”

Her mouth opened wide and her legs contracted. The scream was terrible and more like a tortured animal’s cry than a human voice. It confused him and he made a desperate grab. It was too late.

She didn’t fall. With all her strength she hurled herself from the limb, jumping towards the certain death she preferred to his touch. For a heartbeat she seemed to hang, contorted and fear-crazed, at the apex of her leap, before gravity clutched hold and pulled her crashing down through the leaves. Then Dall was falling too, grabbing for nonexistent handholds.

The safety line he had tried held fast. In a half-daze he worked his way back to the trunk and fumbled loose the knots. With quivering precision he made his way hack to the ground. It took a long time and a blanket was drawn over the deformed thing in the grass before he reached it. He didn’t have to ask if she was dead.

“I tried to stop her. I did my best.” There was a slight touch of shrillness to Dall’s voice.

“Of course, Commander Stane told him, as he spread out the contents of the girl’s waist pouch. “We were watching with the Eye. There was no way to stop her when she decided to jump.”

“No need to talk Slaver to her either -” Arnild said, coming out of the ship. He was going to add something, but he caught Commander Stane’s direct look and shut his mouth. Dali saw it too.

“I forgot!” the young man said, looking back and forth at their expressionless faces. “I just remembered she had understood Slaver. I didn’t think it would frighten her. It was a mistake maybe, but anyone can make a mistake! I didn’t want her to die…”

He clamped his trembling jaws shut with an effort, and turned away.

“You better get some food started,” Commander Stane told him. As soon as the port had closed he pointed to the girl’s body. “Bury her under the trees. I’ll help you.

It was a brief meal, none of them were very hungry. Stane sat at the chart table afterward pushing the hard green fruit around with his forefinger. “This is what she was doing in the tree - why she couldn’t pull the vanishing act like the others. Picking fruit. She had nothing else in the pouch. Our landing next to the tree and trapping her was pure accident.” He glanced at Dall’s face, then turned quickly away

“It’s too dark to see now, do we wait for morning?” Arnild asked. He had a hand gun disassembled on the table, adjusting and oiling the parts.

Commander Stane nodded. “It can’t do any harm - and it’s better than stumbling around in the dark. Leave an Eye with an infra-red projector and filter over the village and make a recording. Maybe we can find out where they all went.”

“I’ll stay at the Eye controls,” Dall said suddenly. “I’m not… sleepy. I might find something out.”

The Commander hesitated for a moment, then agreed. “Wake me if you see anything. Otherwise, get us up at dawn.”

The night was quiet and nothing moved in the silent village of huts. At first light Commander Stane and Dall walked down the hill, an Eye floating ahead to cover them. Arnild stayed behind in the locked ship, at the controls.

“Over this way, sir,” Dall said. “Something I found during the night when I was making sweeps with the Eye.”

The pit edges had been softened and rounded by the weather, large trees grew on the slopes. At the bottom, projecting from a pool of water, were the remains of rusted machinery.

“I think they’re excavation machines,” Dall said. “Though it’s hard to tell, they’ve been down there so long.”

The Eye dropped down to the bottom of the pit and nosed close to the wreckage. It sank below the water and emerged after a minute, trailing a wet stream.

“Digging machines, all right,” Arnild reported. “Some of them turned over and half buried, like they fell in the hole. And all of them Slaver built.”

Commander Stane looked up intently. “Are you sure?” he asked.

“Sure as I can read a label.”

“Let’s get on to the village,” the Commander said, chewing thoughtfully at the inside of his cheek.

Dali the Younger discovered where the villagers had gone. It was really no secret, they found out in the first hut they entered. The floor was made of pounded dirt, with a circle of rocks for a fireplace. All the other contents were of the simplest and crudest. Heavy, unfired clay pots, untanned furs, some eating utensils chipped out of hard wood. Dall was poking through a heap of woven mats behind the fireplace when he found the hole.

“Over here, sir!” he called.

The opening was almost a metre in diameter and sank into the ground at an easy angle. The floor of the tunnel was beaten as hard as the floor of the hut.

“They must be hiding out in there,” Commander Stane said. “Flash a light down and see how deep it is.”

There was no way to tell. The hole was really a smooth walled tunnel that turned at a sharp angle five metres inside the entrance. The Eye swooped down and hung, humming, above the opening.

“I took a look in some of the other huts,” Arnild said from the ship. “The Eye found a hole like this in every one of them. Want me to take a look inside?”

“Yes, but take it slowly,” Commander Stane told him. “If there are people hiding down there we don’t want to frighten them more. Drift down and pull back if you find anything.”

The humming died as the Eye floated down the tunnel and out of sight.

“Joined another tunnel,” Arnild reported. “And now another junction. Getting confused…don’t know if I can get it back the way I sent it in.”

“The Eye is expendable,” the Commander told him. “Keep going.”

“Must be dense rock around… signal is getting weaker and I have a job holding control. A bigger cavern of some sort… wait! There’s someone! Caught a look at a man going into one of the side tunnels.”

“Follow him,” Stane said.

“Not easy,” Arnild said after a moment’s silence. “Looks like a dead end. A rock of some kind blocking the tunnel. He must have rolled it back and blocked the passage after he went by. I’ll back out… Blast!”

“What’s wrong?”

“Another rock behind the Eye - they’ve got it trapped in that hunk of tunnel. Now the screen’s dead, and all I can get is an out-of-operation signal!” Arnild sounded exasperated and angry.

“Very neat,” Commander Stane said. “They lured it in, trapped it - then probably collapsed the roof of the tunnel. These people are very suspicious of strangers and seem to have a certain efficiency at getting rid of them.”

“But why?” Dall asked, frankly puzzled, looking around at the crude construction of the hut. “What do these people have that the Slavers could have wanted so badly? It’s obvious that the Slavers put a lot of time and effort into trying to dig down there. Did they ever find what they were looking for? Did they try to destroy this planet because they had found it - or hadn’t found it?”

“I wish I knew,” Commander Stane said glumly. “It would make my job a lot easier. We’ll get a complete report off to HQ - maybe they have some ideas.”

On the way back to the ship they noticed the fresh dirt in the grove of trees. There was a raw empty hole where the girl had been buried. The ground had been torn apart and hurled in every direction. There were slash marks on the trunks of the trees, made by sharp blades… or giant claws. Something or somebody had come for the girl, dug up her body and vented a burning rage on the ground and the trees. A crushed trail led to an opening between the roofs of one of the trees. It slanted back and down, its dark mouth as enigmatic and mysterious as the other tunnels.

Before they retired that night, Commander Stane made a double check that the ports were locked and all the alarm circuits activated. He went to bed but didn’t sleep. The answer to the problem seemed tantalizingly obvious, hovering just outside his reach. There seemed to be enough facts here to draw a conclusion from. But what? He drifted into a fitful doze without finding the answer.

When he awoke the cabin was still dark, and he had the feeling something was terribly wrong. What had awakened him? He groped in his sleep-filled memories. A sigh. A rush of air. It could have been the cycling of the air lock. Fighting down the sudden fear he snapped on the lights and pulled his gun from the bedside rack. Arnild appeared, yawning and blinking in the doorway.

“What’s going on?” he asked.

“Get Dall - I think someone came into the ship.”

“Gone out is more like it,” Arnild snuffed. “Dall’s not in his bunk.”

“What!”

He ran to the control room. The alarm circuit had been turned off. There was a piece of paper on the control console. The Commander grabbed it up and read the single word written on it. He gaped as comprehension struck him, then crushed the paper in his convulsive fist.

“The fool!” he shouted. “The damned young fool! Break out an Eye. No, two! I’ll work the duplicate controls!”

“But what’s happened?” Arnild gaped. “What’s young Dall done?”

“Gone underground. Into the tunnels. We have to stop him!”

Dall was nowhere in sight, but the lip of the tunnel under the trees was freshly crumbled.

“I’ll take an Eye down there,” Commander Stane said. “You take another one down the next nearest entrance. Use the speakers. Tell them that we are friends, in Slaver.”

“But - you saw what reaction the girl had when Dall told her that.” Arnild was puzzled, confused.

“I know what happened,” Stane snapped. “But what other choice do we have? Now get on with it!”

Arnild started to ask another question, but the huddled intensity of the Commander at the controls changed his mind. He sent his own Eye rocketing towards the village.

If the people hiding in the maze of tunnels heard the message, they certainly didn’t believe it. One Eye was trapped m a dead-end tunnel when the opening behind it suddenly filled with soft dirt. Commander Stane tried nosing the machine through the dirt, but it was firmly trapped and held. He could hear thumpings and digging as more dirt was piled on top.

Arnild’s Eye found a large underground chamber, filled with huddled and frightened sheep. There were none of the natives there. On the way out of this cavern the Eye was trapped under a fall of rocks.

In the end, Commander Stane admitted defeat. “It’s up to them now, we can’t change the end one way or another.”

“Something moving in the grove of trees, Commander,” Arnild said sharply. “Caught it on the detector, but it’s gone now.”

They went out hesitantly with their guns pointed, under a reddened dawn sky. They went, half-knowing what they would find, but fearful to admit it aloud while they could still hope.

Of course there was no hope. Dall the Younger’s body lay near the tunnel mouth, out of which it had been pushed. The red dawn glinted from red blood. He had died terribly.

“They’re fiends! Animals!” Arnild shouted. “To do that to a man who only wanted to help them. Broke his arms and legs, scratched away most of his skin. His face-nothing left.. “The aging gunner choked out a sound that was half gasp, half sob. “They ought to be bombed out, blown up! Like the Slavers started…” He met the Commander’s burning stare and fell silent.

“That’s probably just how the Slavers felt,” Stane said. “Don’t you understand what happened here?”

Arnild shook his head dumbly.

“Dall had a glimpse of the truth. Only he thought it was possible to change things. But at least he knew what the danger was. He went because he felt guilty for the girl’s death. That was why he left the note with the word slaves on it, in case he didn’t come back.”

“It’s really quite simple,” he said wearily, leaning back against a tree. “Only we were looking for something more complex and technical. When it wasn’t really a physical problem, but a social one we were facing. This was a Slaver planet, set up and organized by the Slavers to fit their special needs.”

“What?” Arnild asked, still confused.

“Slaves. They were constantly expanding, and you know that their style of warfare was expensive on manpower. They needed steady sources of supply and must have created them. This planet was one answer. Made to order in a way. A single, lightly forested continent, with few places for the people to hide when the slave ships came. They planted a nucleus, gave the people simple and sufficient sources of food, but absolutely no technology. Then they went away to let them breed. Every few years they would come back, take as many slaves as they needed, and leave the others to replenish the stock. Only they reckoned without one thing.”

Arnild’s numbness was wearing off. He understood now.

“The adaptability of mankind,” he said.

“Of course. The ability - given enough time-to adapt to almost any extreme of environment. This is a perfect example. A cut-off population with no history, no written language-just the desire to survive. Every few years unspeakable creatures drop out of the sky and steal their children. They try running away, but there is no place to run. They build boats, but there is no place to sail to. Nothing works…”

“Until one bright boy digs a hole, covers it up and hides his family in it. And finds out it works.”

“The beginning,” Commander Stane nodded. “The idea spreads, the tunnels get deeper and more elaborate when the Slavers try to dig them out. Until the slaves finally win.”

This was probably the first planet to rebel successfully against the Greater Slavocracy. They couldn’t be dug out. Poison gas would just kill them and they had no value dead. Machines sent after them were trapped like our Eyes. And men who were foolish enough to go down…” He couldn’t finish the sentence, Dall’s body was stronger evidence than words could ever be.

“But the hatred?” Arnild asked. “The way the girl killed herself rather than be taken.”

“The tunnels became a religion,” Stane told him. “They had to be, to be kept in operation and repair during the long gap of years between visits by the Slavers. The children had to be taught that the demons come from the skies and salvation lies below. The opposite of the old Earth religions. Hatred and fear were implanted so everyone, no matter how young, would know what to do if a ship appeared. There must be entrances everywhere. Seconds after a ship is sighted the population can vanish underground. They knew we were Slavers since only demons come from the sky.”

“Dall must have guessed part of this. Only he thought he could reason with them, explain that the Slavers were gone and that they didn’t have to hide any more. That good men come from the skies. But that’s heresy, and by itself would be enough to get him killed. If they ever bothered to listen.”

They were gentle when they carried Dall the Younger back to his ship.

“It’ll be a job trying to convince these people of the truth.” They paused for a moment to rest. “I still don’t understand though, why the Slavers wanted to blow the planet up.

“There too, we were looking for too complex a motive,” Commander Stane said. “Why does a conquering army blow up buildings and destroy monuments when it is forced to retreat? Just frustration and anger, old human emotions. If I can’t have it, you can’t either. This planet must have annoyed the Slavers for years. A successful rebellion that they couldn’t put down. They kept trying to capture the rebels since they were incapable of admitting defeat at the hands of slaves. When they knew their war was lost, destruction of this planet was a happy vent for their emotions. I noticed you feeling the same way yourself when you saw Dall’s body. It’s a human reaction.”

They were both old soldiers, so they didn’t show their emotions too much when they put Dall’s corpse into the special chamber and readied the ship for takeoff.

But they were old men as well, much older since they had come to this planet, and they moved now with old men’s stiffness.