In 2267, after a bad afternoon failing to trap a rabbit-like creature and being chased by a beast, Apella was approached by Krell, who identified himself as a traveler from a foreign land called the Klingon Empire. Krell became Apella's mentor and gave him a flintlock musket, a significant advance over the bows and arrows then used on the planet. Krell would return several times over the next ten months to secretly arm Apella and defy the Organian Peace Treaty. (TOS - Klingons: Blood Will Tell comic: "The Order of Things")
Apella became the leader of his village, directing his people toward the Klingon way of life and conflict with the neighboring hill people. But Krell's presence was exposed by James T. Kirk, forcing the Klingon to depart. Kirk armed the hill people with weapons equal to those of Apella. (TOS episode & novelization: A Private Little War)
Two months later, when Krell returned, Apella's village was in flames. Apella asked for further technology. Krell refused, but proclaimed that Apella and his villagers had become true warriors. (TOS - Klingons: Blood Will Tell comic: "The Order of Things")
- TOS episode & novelization: A Private Little War
- TOS - Klingons: Blood Will Tell comic: "The Order of Things"