who is the writer?
William Tenn
Future Science Fiction and Science Fiction Stories
 "The Liberation of Earth" by William Tenn, and "If I Forget Thee, Oh Earth" by Arthur C. Clarke.
what is future science fiction and science fiction stories? Two American science fiction magazines. who was its editor? Charles Hornig when was it initially published? End of the 1930s. who owns it? Louis Silberkleit can you name any works they published? "The Liberation of Earth",  "If I Forget Thee, Oh Earth" can you summarize the plot of the first work? It portrays Earth as the battleground between two powerful alien races, the Troxxt and the Dendi, who repeatedly "liberate" it from each other.
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Future Science Fiction and Science Fiction Stories [SEP] Introduction
He was more successful than Hornig in obtaining good stories, partly because he had good relationships with several well-known and emerging writers. Among the better-known stories he published were "The Liberation of Earth" by William Tenn, and "If I Forget Thee, Oh Earth" by Arthur C. Clarke.