... First, the sheer adventure. Gant is a mountain man, circa 1840. He is Jeremiah Johnson, living in the wrong century. Despite his heavy drinking, volcanic mood swings and numerous wounds, he survived more than 40 months of combat. In 2003 and again in 2011, he and a dozen Special Forces soldiers lived in a mountain village in eastern Afghanistan, adjacent to the Pakistan border. When I visited that village, both the elders and the soldiers from the 1st Battalion of the 32nd Infantry told tales about Gant’s exploits. He captured one insurgent after a two-day chase. Another time, he...