Through Space With HG Wells And His Successors

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In The War Of The Worlds by HG Wells, Martians invade Earth and Venus.

In Star-Begotten by Wells, Planetarium Club members discuss cosmic rays and Martians before one of their number summarizes and criticizes The War Of The Worlds, mistakenly attributing it to "'...Conan Doyle, Jules Verne, one of those fellows...'" (New York, 1975, p. 48), then proposes instead Martianization of human beings by cosmic rays.

In the Ransom Trilogy by CS Lewis, a scientist visits Mars and Venus, in the latter case as the spearhead of a planned demonic invasion. Lewis parenthetically comments that "...Mr Wells' Martians [are] very unlike the real Malacandrians..." (Voyage to Venus, London, 1978, p. 7).

In The War Of Two Worlds by Poul Anderson, Martians militarily conquer Earth but are being covertly manipulated by extrasolars.

In "Soldier From The Stars" by Anderson, humanoid extrasolars conquer Earth economically by selling their superior military services to the highest bidder among Terrestrial governments.

Later, I will add a few more alien invasions but I think that this is a neat progression through Wells, Lewis and Anderson. See here.