In early 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 Klingon 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. In December 2267, 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 & Star Trek 10 novelization: A Private Little War)
Two months later, when Krell reappeared, 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")
However, eventually Krell returned and established a small outpost to export leutrinium metal. Apella grew power-hungry and united 20 tribes, greatly expanding his village into the city of Victory, which he named for its psychological value after a word Nona spoke before her death. Governor Apella was responsible for maintaining a production quota for the mine and smelting plant using slave labor. He saw himself as a partner to Krell.
In 2273, Krell spotted Kirk in surveillance footage and singled him out to Apella as representing forces against the Klingon Empire. Apella ordered a hunting party to capture Kirk but it failed, and Apella began to realize he was a puppet who would never earn the respect he wanted. When Apella discovered Kirk among newly-captured slaves, he kept that knowledge from Krell. A week later, hundreds of Freeholders broke through the perimeter of the mine to free the slaves. During the fighting, Kirk convinced Apella that Neural's resources belonged to Neural, not the Klingon Empire. He joined with Tyree to call an end to the fighting and order the Klingons off the planet. Apella rode with Kirk aboard a Klingon freighter which Kirk used to destroy the smelting plant. Apella and Tyree agreed to rebuild the facility in a spirit of cooperation, using the leutrinium as a resource for interstellar trade. (TOS novel: Serpents in the Garden)
- TOS episode & Star Trek 10 novelization: A Private Little War
- TOS - Klingons: Blood Will Tell comic: "The Order of Things"
- TOS novel: Serpents in the Garden