Note: According to a Simak interview published in Muriel R. Becker's Clifford D. Simak: A Primary and Secondary Bibliography (1980), the first version of this novel was written by John W. Campbell, Jr. when Campbell was "something like eighteen years old", i.e. in the late 1920s. That version remains unpublished. After Campbell, then the editor of ''Astounding'', serialized Simak's "Cosmic Engineers" in early 1939, he gave the manuscript of ''Empire'' to Simak to see if Simak could rewrite it. Simak did rewrite the novel, but Campbell decided that the new version wasn't suitable for publication either. In 1951 H. L. Gold, the editor of the SF magazine ''Galaxy'', was looking for material for his Galaxy Science Fiction Novel series of standalone novels. He had heard about ''Empire'' from Campbell and approached Simak to see if he could buy it. Simak asked Campbell if Campbell wanted to share the credit and the money, but Campbell refused. In the end, ''Empire'' appeared in ''Galaxy Science Fiction Novel #7'' as by Simak alone.