On May 12, a few days after street fighting erupted in Beirut, I drove to Majd al Anjar, a Sunni stronghold in Lebanon’s Bekaa, close to the Syrian border, where gunmen were still blocking the motorway from Beirut to Damascus. At the edge of town, several hundred men with automatic rifles, rocket propelled grenade launchers, pistols and hand grenades stood before earthen barriers and fires. Some wore masks. There was nobody in command – this was a mob, not a militia. The men were angry, afraid, suspicious, shouting at strangers and each other, each one an authority unto himself, carelessly...