Some of those men and women answer the call because they think it’s their duty, whether they like it or not. Some go because it’s a good way to advance their careers, or because they like the extra money they get with combat duty. Others just like it. “Soldiers want to fight,” says retired Gen. Barry McCaffrey, who was the youngest and most decorated Army general when he retired in 1996. “That’s why they signed up.”

First Sgt. Jason Dodge is that kind of soldier, an extreme guy in every respect. He gets to his office between 0425 and 0428. A few hours later, he’s on his morning run—usually 10 to 15 miles. He can climb a 30-foot rope using just his arms in 10 seconds. He works best in a room without direct sunlight, he says, and doesn’t like to eat more than one meal a day—”and that’s dinner with my wife, but only because she makes me.” His job: to engineer explosives to blow down doors and walls.