And so the reckoning begins. Only hours after a special task force concluded on Wednesday that “systemic failures and leadership and management deficiencies” may have contributed to the deaths of Ambassador Chris Stevens and three other Americans in Benghazi, Libya, the State Department’s security chief resigned and three other officials were relieved of their duties. What was lacking in the report, however, was any sense of who was responsible farther up the chain. Secretary of State Hillary Rodham Clinton’s Accountability Review Board—chaired by retired Ambassador Thomas R. Pickering and vice chaired by another national-security heavyweight, former Joint Chiefs Chairman Michael...