As the weakly protected U.S. diplomatic compound in eastern Libya came under attack the night of Sept. 11, 2012, the deputy head of the embassy in Tripoli 600 miles away sought in vain to get the Pentagon to scramble fighter jets over Benghazi in a show of force that might have averted a second attack on a nearby CIA complex. Hours later, according to excerpts of the account by the U.S. diplomat, Gregory Hicks, American officials in the Libyan capital sought permission to deploy four U.S. special operations troops to Benghazi aboard a Libyan military aircraft early the next morning....