The Iraq war may have never been declared lost. But the stunning surge in violence over the past year — and the return of al-Qaeda in the western province of Anbar this month — is forcing Americans who invested personally in the war’s success to grapple with haunting questions.

“Could someone smart convince me that the black flag of al-Qaeda flying over Fallujah isn’t analogous to the fall of Saigon?” former Army captain Matt Gallagher asked on Twitter. “Because. Well.” …

This week, muddled accounts of fighting between al-Qaeda militants, tribesmen and Iraqi troops thrust Iraq back into the headlines. At Camp Lejeune, N.C., a 30-year-old Marine staff sergeant who served tours in Fallujah and Ramadi found himself seething. He thought about his mind-set on his first deployment, when he was fresh out of basic training.

“I was terrified half the time,” said Paul, who asked to be quoted only by his first name because he now serves in a Special Operations regiment. “The way my 20-year-old self envisioned it, I was fighting evil in the world, in a place where people are being treated terrible and getting murdered and have zero rights.”

In hindsight, that idealism seems absurd, and the memories painful.