In from the Cold

Until this week, only a few things about the strange, long-ago disappearance of Charles Robert Jenkins were known beyond a doubt. In the bitter cold of Jan. 5, 1965, the 24-year-old U.S. Army sergeant was leading a night reconnaissance patrol near the Demilitarized Zone (DMZ) that separates North Korea from South Korea. At around 2:30 a.m., he told his radioman and another soldier he was going to investigate the road up ahead. He disappeared down the hill—and never came back.

Beyond that, almost everything about the small, jug-eared infantryman—from his motivations to what his life in the North...