CAIRO — A militia in Benghazi, Libya, tied to the killing of Ambassador J. Christopher Stevens fled its headquarters on Monday after an hourslong gun battle with a local military unit, a potential turning point in a continuing struggle between Islamists and their foes for control of the city. At least nine people were killed and more than 50 were wounded, health officials said, as the battle flared out across Benghazi, beginning before dawn. Stores and schools were closed. The local authorities advised residents to stay in their homes and avoid the streets. And by late afternoon, the militia, Ansar al-Shariah, appeared to have disappeared underground. Photographs circulated over the Internet that appeared to show its headquarters emptied and smoking, with the wreckage of a burned-out car sitting outside. The melee followed the deaths of more than 40 people in a similar battle in Tripoli this month, when militiamen […]