The young Army infantry recruits lined up in full combat gear, guns at the ready. At the signal, a soldier in front kicked in the door and they burst into the room, swiveling to check around the walls for threats. “You’re dead!” one would-be enemy yelled out from a dark corner, the voice slightly higher than the others echoing through the building. It was 18-year-old Kirsten, training to become one of the Army’s first women serving as infantry soldiers. “I want to be one of the females to prove to everybody else that just because you’re a female, doesn’t mean...