The cyborg code-named "Slant" was sent out as an Independent Reconnaissance Unit during an interstellar war between Earth and its colonies. The fighting ended three hundred years ago, but Slant's computer does not admit this - he is compelled to carry on as if the war were still raging.
Then he comes across a planet where his sensors register "gravitational anomalies." The computer interprets these as enemy weapons research.
The local inhabitants call the anomalies "magic."