Arronus VII was a planet located along the Federation-Klingon border around fifty light-years from Earth. It was quite rich in mineral deposits.
In the first year of James T. Kirk's command of the USS Enterprise, the starship visited the planet on a survey mission. A small survey party consisting of Lieutenants Lee Kelso and Dezago beamed down and found that a squad of Klingons was also conducting a survey mission. Outmanned, Kelso and Dezago fled into the jungle, and Dezago was injured. However, Kelso kept fighting and kept the Klingons at bay in time for Captain Kirk and Lieutenant Commander Spock to arrive with reinforcements. (TOS - My Brother's Keeper novel: Constitution)