After the enjoyable Master Mind and its initial appearance in 1927, there remained five volumes in the Martian series, three real novels, one “novel” composed of four interconnected shorter tales from Amazing, and a final, posthumous volume containing two additional novelettes.
The first of these remaining books was A Fighting Man of Mars, written in 1929, serialized in Blue Book the next year, and published in book form the year following. In introducing this tale Burroughs doubled and redoubled the complexities of his interlocking series by explaining that when Jason Gridley left Tarzana, California, for Africa, in order to convince Tarzan to accompany him to Pellucidar, he had left an automatic transmitter and receiver turned on in his Tarzana laboratory.
The set endlessly broadcasted Gridley's initials. The receiver was set to pick up whatever reply Gridley might receive—previously it had been Abner Perry's distress call from Pellucidar, this time it might be a message from Barsoom.
During Gridley's absences from Tarzana, Burroughs dropped in occasionally to see that all was well in the lab, and on one such visit found the receiver operating at full speed, bringing in a Morse-coded message. Over a decade earlier Burroughs and Cogdon Nestor had needed a telegrapher to translate David Innes' message to them in the Sahara, as recorded in Pellucidar. Apparently Burroughs had taken a lesson from that experience, and studied Morse in the intervening time, for he was able to transcribe the Gridley Wave message as it came in.
The transmission itself was made by Ulysses Paxton/Vad Varo, but the story was that of Tan Hadron of Hastor, the Martian fighting man of the book's title. Basically A Fighting Man of Mars falls into the same category as Thuvia, Chessmen, and Master Mind. None of these four middle novels of