He hailed the car carrying the feared leader of Al Qaeda in the neighborhood, a man known as the White Lion, on one of Amariyah’s main streets. “We want you to stop destroying our neighborhood,” he told the man.

“Do you know who you are talking to?” said the White Lion, getting out of his car. “I am Al Qaeda. I will destroy even your own houses!”

He pulled out his pistol and shot at Abul Abed. The gun jammed. He reloaded and fired again. Again, the gun jammed.

By this time, Abul Abed said, he had pulled his own gun. He fired once, killing the White Lion.

“I walked over to him, stepped on his hand and took his gun,” Abul Abed, which is a nom de guerre, said at his new, pink-painted headquarters in a renovated school in Amariyah, as an American Army captain seated in the corner nodded his head in affirmation of the account. “And then the fight started.”