By Sam Dagher DAMASCUS, Syria–Militants from the Sunni extremist group that calls itself the Islamic State have captured Syria’s largest oil field and now hold nearly half of the northeastern province of Deir-Ezzour after monthslong battles with other rebel factions, according to opposition activists, rebels and local residents The fighting has intensified in recent days on the back of gains in neighboring Iraq by the militants, who formerly called themselves the Islamic State of Iraq and al-Sham, or ISIS. Videos posted on jihadist websites showed black-clad fighters who identified themselves as belonging to the Islamic State standing at the entrance of a facility leading to the site of the Al-Omar oil field in eastern Syria. “They fled like rats,” says one of the fighters, referring to members of its rival, the al Qaeda-linked Nusra Front, which captured the field, considered the largest in Syria in terms of production, from […]