Looking for a story where an intelligent robot tries to avenge the human race

Question

This was a short story probably written well before 2010. I have an idea that it might be fairly well-known, but haven't managed to find it.

It started in the not-too-distant future. There was a permanent research base on the moon run by human staff with one experimental self-aware robot. I think the robot was called Sam.

The base crew was recalled to Earth at the outbreak of war, which surprised Sam as "he" had been told that war had been eradicated. The war eventually wiped out the human race and he came to believe that it had been done by hostile aliens, partly because of a well-written sci-fi book he mistook for fact. He used an automated factory on Earth to build an army of robots and led them on a mission to seek and destroy the aliens.

After centuries of travelling space and wiping out any moderately advanced civilisation they found, some robot researchers discovered that there had been no alien attack and the human race had destroyed itself. Sam concluded that his own race needed an overriding purpose to keep it from meeting the same fate, so he instructed the researchers to destroy the evidence and continued the impossible revenge quest.

Answer 1

To Avenge Man by Lester Del Rey. I read it in The Ninth Galaxy Reader but it has been widely anthologised so you could have read it in lots of different collections.

The story is exactly as you describe. At the end Sam is told:

"There is no Enemy now," the scientist said from behind him. "There can be no doubt. Man was his own destroyer. He killed himself. In a sense, his race was the one we are sworn to kill."

but Sam responds by burning the evidence and the story ends:

Man had failed, like all other races grown from killing strains of animal life. But in dying, he had passed on part of his soul to another race that had been designed without his mighty passions. Somehow he had passed on the driving anger of his spirit to his true children, the robots.

And they had carried on.

The robots had been a created race, a race designed only to serve, able to live in perfect peace and without ambition. They had owned no heritage. But through an accident of fiction and a few dying words, men had left them a rich heritage.

Anger had carried them throughout the stars, and hatred had bridged the spaces between the galaxies.

‘You’re mistaken, Robert,’ Sam said. ‘Vengeance is our heritage. Burn the evidence.’ Most of the material was tinder dry, and it caught fire at the first spark. For a few seconds, it was a seething pillar of flame. Then there was only a dark scar on the wood to show the true death of man.