he reveals the source of his conflict with Lokai. Like himself, all of Bele's people on Cheron are black on their right sides, while Lokai's people are all white on their right sides. The distinction is lost on the ship's officers, who query whether the original Cheronians were monochromatic like the crew of the Enterprise, and leave the legal matter for authorities at the next starbase to decide, as the Federation has no extradition treaties with Cheron, and the case requires due process. Once the Ariannus mission is completed, Bele takes control of the Enterprise again, this time disabling the self-destruct system. When the ship arrives at Cheron, Spock can find no sign of intelligent life. Lokai and Bele realize they are each the only ones left of their peoples, who have completely annihilated themselves in civil war. Enraged, they attack each other, their force fields threatening to damage the ship. Lokai breaks away, Bele pursues him, both traumatically envisioning their destroyed planet as they do so, and the two eventually beam down to the planet. The bridge crew remark sadly on their unwillingness to give up their hate. Production The script for the story was developed from a story outline written by Gene L. Coon under his pen name Lee Cronin. This was Gene Coon's final episode. Although Gene Roddenberry liked it, it was initially rejected by NBC studio executive Stanley Robertson. The look of the aliens Bele and Lokai was decided only a week before filming began, based on an offhand comment by director Jud Taylor. The half white-half black makeup led to criticism of the episode as heavy-handed. The script evolved from an outline by Barry Trivers for a possible first season episode called "A Portrait in Black and White". The script was accepted for the third season following budget cuts. "Let That Be Your Last Battlefield" is significant in the Star Trek universe for the first appearance of a self-destruct system (as opposed to an improvised self-destruction process). It did not originate the concept, which appeared previously in the film Forbidden Planet (1956), but the self-destruct system has appeared as a plot device in many subsequent Star Trek stories. The self-destruction sequence codes 11A, 11A2B, 1B2B3 and the final code 000 destruct-0 from the episode were used again verbatim in Star Trek III: The Search For Spock to destroy the Enterprise in that film. Reception In