As Americans fought for their lives in Benghazi, Libya, the Pentagon’s options for direct intervention were narrowed to one: a fleet of F-16 fighters parked across the Mediterranean at NATO's air base in Aviano, Italy. How the best military in the world came to having only one real choice in a terrorist attack that killed the U.S. ambassador to Libya and three other U.S. citizens is the story of an ill-equipped commander. U.S. Africa Command, which oversees military options in North Africa, had no access to AC-130 gunships or to armed drones, such as the Predator, that could have killed...