The cruiser returned home to find the planet occupied by an invading force of frogmen and most of their people slaughtered. Dalbar wanted to launch a surprise attack and free the remaining native population, but his ship was damaged in the jungle and unable to take off. They chose to make surreptitious surgical strikes against the frogmen, pretending to be jungle savages armed only with bows and arrows.
In 2265, Dalbar rescued James T. Kirk and Spock from a frogman patrol, but one frogman escaped and radioed for reinforcements. Spock helped repair Dalbar's cruiser just in time for the ship's force fields to defend against an attack, and Dalbar launched his ship to drive the frogmen out of Muton's capital city. He and his crew then freed imprisoned natives kept as slaves.
Dalbar was proud to have completed the first step in their struggle. Kirk expected Dalbar would have a tough fight before the frogmen were driven off his planet, but Dalbar insisted they would succeed. He gave Kirk and Spock a transport to return to the USS Enterprise, which was in an adjacent star system. (TOS comic: "Slaves of the Frogmen")