Correction: An earlier version of this story incorrectly stated the year the United States initiated its troops “surge” in that country. It was 2007, not 2009.

The towering former three-star general keeps a wooden box on his desk with the photos of 257 service members who died in Iraq under his command, sorted by date. During quiet moments, usually a couple of times a week, Mark Hertling opens the lid, inscribed with the words “Make it Matter,” flips through the laminated portraits of uniformed troops and reflects on their loss.

“I try to keep track of anniversaries of the deaths and say a prayer for them and their families,” said Hertling, who now works at a hospital in Orlando. “During the holiday season, you think about the young men and women killed in 2003, 2004 and figure they would have been in their 30s now, with a couple of kids.”

The ritual was never easy. It has become increasingly painful over the past two years, as Hertling and a generation of troops and civilians indelibly shaped by harrowing tours in Iraq have watched the country unravel from afar.

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.”

Gallagher, 30, who left the Army to pursue a writing career in New York, has kept close tabs on Iraq since the end of his deployment as a platoon commander in the outskirts of Baghdad in 2009. He has a Google alert for Saba al-Bor, a small village northwest of Baghdad where his infantry platoon spent 15 months living in terror of armor-penetrating roadside bombs and in awe of the complexities of tribal politics.

Gallagher, who was part of the troop surge ordered by the George W. Bush administration, felt his stomach churn a couple of months ago when an alert prompted him to click on a video of a suicide bombing in his old battleground. He had the same reaction watching grainy footage of masked al-Qaeda militants raising the black flag of jihad in Fallujah.

He said he has gradually come to accept that the sustained peace he and fellow soldiers had fought for has not lasted.

“It’s a very disconcerting and ugly thing to reconcile as an individual,” said Gallagher, who kept a vivid and popular blog during his deployment.

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.

“It brings back a lot of anger,” Paul said. “I feel like it’s been a big waste of time. It’s kind of like, why the hell did all my buddies die there for? There’s no purpose to it.”

This week, Gen. Ray Odierno, the head of the Army and one of the architects of the 2007 troop surge he and others came to see as a strategic success, was asked whether the United States should consider deploying troops to Iraq once again. No, he said. The general called the situation in Iraq disappointing, summing it up using language that commanders used in the past to explain what Americans fought and died to avoid over a decade of war.

“The big threat to our national security is ungoverned territory, areas where we have terrorist organizations that become dominant and then try to export their terrorism outside the Middle East and into several other countries, including the United States,” he said at a National Press Club luncheon Tuesday.

Odierno’s longtime political adviser in Iraq, an Arabic­speaking Briton who now teaches Middle East politics at Yale University, was speechless when she caught a glimpse of news footage of Anbar while working out recently. Emma Sky has long considered the Iraq war lost, but the sight was bloodcurdling.

“It brought back memories of Iraq’s darkest days, which we all hoped had been left behind,” she said. “So many U.S. soldiers put their lives and souls into giving Iraqis hope for a better future than they had under Saddam.”

America’s role in the Iraq war ended with little fanfare. Months before the last troops crossed the border into Kuwait, the U.S. military began calling the mission there Operation New Dawn. Commanders portrayed American troops as advisers and enablers, rather than combatants, and said the war was now for the Iraqis to win or lose.

There were no victory parades or symbolic displays of jubilation to mark the end of an awful conflict from which 4,486 American troops returned in coffins. A couple of months after the pullout, President Obama hosted Iraq veterans at the White House to honor their service. Vice President Biden declared to those in attendance: “You adapted, you succeeded and you defeated.” Then Obama, dressed in a tuxedo, took to the podium, flanked by a golden curtain.

“In one of our nation’s longest wars, you wrote one of the most extraordinary chapters in American military history,” the commander in chief said. “Now the Iraqi people have a chance to forge their own destiny, and every one of you who served there can take pride in knowing you gave the Iraqis this opportunity; that you succeeded in your mission.”

To many veterans, those words now ring hollow.

They don’t entirely to Hertling, who continues to hope that Iraq will somehow pull through. But he’ll always be troubled by the toll the conflict took on his family. Hertling, his two sons and a daughter-in-law spent a total of 12 years deployed in Iraq. Each son lost a soldier in his platoon, deaths that scarred them for life, he said. The Hertlings have been wrestling this week with the question of what it was all for.

“You bounce back and forth between: Was it a complete failure, or did we do the best we could and handed it over to them when things were relatively calm?” he said. “Every person who served in Iraq or Afghanistan never loses that part of them when they come home. It becomes part of their soul.”