On November 29, Syrian rebels breached the western limits of Aleppo, Syria’s largest city in the north, which had suffered the greatest destruction of any other city in the country’s thirteen-year-long civil war. The offensive triggered the “death spiral” of Bashar al-Assad’s regime, as a mixed coalition of former rebels, local strongmen, and regular people, suddenly emboldened, captured the southern city of Daraa, near the border with Jordan. Rebels from the north, led by the Islamist faction Hayat Tahrir al-Sham...