It was the Mogadishu moment of the Iraq war. March 31, 2004: Four American mercenaries are ambushed in the Sunni hotbed of Fallujah, their jeeps set ablaze with the men inside. An angry mob drags their charred corpses through the streets, hanging them from a bridge over the Euphrates River. "Fallujah is the graveyard of the Americans!," the mob declares in front of the cameras. Within hours, the images spread across the world. The ensuing US slaughter in Fallujah would fuel the fierce Iraqi resi...