The February 17th Martyrs Brigade, a Benghazi-based militia with Islamist elements that the State Department hired as a “quick reaction force” (QRF) to protect the department’s mission in Benghazi, warned the State Department that it would not protect the movements of Amb. Chris Stevens when he visited there last September. That warning was relayed to the regional security officer (RSO) at the U.S. Embassy in Tripoli—the top security adviser to the ambassador—in an internal State Department email dated Sept. 9, 2012. That was one day before Stevens departed Tripoli for Benghazi—for what was scheduled to be a five-day visit. …