John Carter debuted in "A Princess of Mars", written in 1911, then serialized as "Under the Moons of Mars", February to July 1912 in the pulp magazine "All-Story", before being published in book form, October 1917.
The character reappeared in subsequent volumes of the series, including "The Gods of Mars (1918), "The Warlord of Mars" (1919), "Swords of Mars" (1936) and "Llana of Gathol (1948). Carter is also a major secondary character in the fourth volume, "Thuvia, Maid of Mars" (1920), and the ninth, "Synthetic Men of Mars" (1940).
According to Burroughs, Carter served as a captain in the American Civil War on the side of the Confederacy. After the war, he struck it rich finding gold in Arizona. But while hiding from Apaches in a cave, he seemingly dies, leaving his inanimate body behind, then mysteriously transported by astral projection to the planet Mars.
Re-embodied in a form identical to his earthly one, Carter is much stronger than the natives of Mars, because of the difference in gravity.
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