SciFi for pre-teens (Score 1)

The Warlord of Mars - science fiction novel written by Edgar Rice Burroughs, the third of his famous Barsoom series. Burroughs began writing it in June, 1913, going through five working titles; "Yellow Men of Barsoom," "The Fighting Prince of Mars," "Across Savage Mars," "The Prince of Helium," and "The War Lord of Mars." Old but I still remember these and
it has been at least 50 years since I read the series.