As a 19-year-old, Rettig had a prominent guest-starring role in the January 1961 "Wagon Train" episode "Weight of Command". Then in its fourth season on NBC, "Wagon Train" was the second highest-rated series that year on American network television. The Rettig played the part of a 16-year-old boy, Billy, who is traveling with his family on the wagon train. Although his father reluctantly allows his son to go on a buffalo hunt with assistant trailmaster Bill Hawks (Terry Wilson), Billy frets that his father doesn't think of him as a man yet. When the hunters are attacked by a band of renegade Indians, they take refuge in an empty house. Hawks manages to escape, but Wagonmaster Seth Adams (Ward Bond) makes the difficult decision not to attempt Billy's rescue, lest the entire wagon train be vulnerable to attack. Hawks, who had promised Billy he would be rescued, is outraged by the decision to abandon the besieged youth to his fate. When Billy manages to survive the Indian attack on his own, he earns his father's respect.