For more than 30 years, the A-10 Thunderbolt II—better known as the Warthog because it’s so ugly—has performed a crucial role: attacking hostile targets that threaten troops on the ground, a task called close air support. The plane, designed for the Cold War, is old. It’s slow. And it’s about as sophisticated as a hammer. But it is heavily armored and wickedly armed, making it a ruthlessly effective weapon. And that is why, despite ongoing efforts by Defense Department brass to kill it, the Warthog is headed back into battle to help in the fight against ISIS.