"The Liberation of Earth" is a science fiction short story by American author William Tenn, written in 1950, first published in 1953, and reprinted several times in various anthologies, including 1955 collection Of all Possible Worlds and 1967 anthology The Starlit Corridor. The story, which Tenn described as having been inspired by the Korean War, describes Earth becoming a battleground between two powerful alien races who repeatedly "liberate" it from each other. Source: Wikipedia (en)