It was late 2010, and Sgt. Philip A. McCulloch Jr. was locked into what may have been the darkest battle of America's longest war.

The gauntly thin 22-year-old squad leader for Kilo Company, 3rd Battalion, 5th Marines, had gotten too used to seeing the men in his unit killed by roadside bombs or enemy fire in the Sangin valley, a hotly contested district in Afghanistan's Helmand province that buzzed with insurgent activity. He didn't allow himself to feel grief; he just got angry.

That anger boiled over when Cpl. Tevan Nguyen, 21, was killed by an improvised explosive device Dec. 28, shortly before the unit would return home. Nguyen's death was the result of treachery, McCulloch said. Taliban representatives had brokered a temporary cease-fire with the unit, surrendering weapons and claiming they had cleared IEDs from the area where 3/5 Marines patrolled.

When it became clear that the deal had been a lie, "it was game on," McCulloch said. "We made sure that we went out there and let them know they made a mistake. And they paid for it with their lives and a lot of blood, a lot."

Just over a week later, McCulloch, fueled by his emotion, would earn the Silver Star for exceptional valor in the face of death while leading an aggressive six-hour pursuit of the enemy that culminated in a dramatic air assault. When it was over, the battlefield was littered with dead Taliban fighters and their motorcycles.

Four years later, McCulloch still feels the loss of his brothers-in-arms. But he no longer believes the war they fought together was worth the cost they paid. As news broke in late October that the Marines had concluded their combat operations, McCulloch's skepticism and frustration regarding Afghanistan appears to be the rule rather than the exception. A half-dozen active-duty Marines who spoke with Marine Corps Times are unanimous in their belief that it is time for U.S. forces to pull out of the country after 13 years of combat. But most expressed doubt about the country's ability to sustain progress.

McCulloch stays in touch with his Afghan interpreter from Sangin, whom he says receives daily death threats now that the Marines have pulled out. Despite positive reports about the development, improvement and fighting spirit of the Afghan National Army's 215th Corps, which took over for the Marines in Helmand province, McCulloch said he has little faith in their mettle based on his own experiences working with them in 2010 and 2011. He feels the Marines' counterinsurgency strategy, with its village shuras, cash investments and focus on building local trust and relationships made them less effective at defeating the enemy.

And above all, he believes that no amount of time would be sufficient to win a "thousand-year war" fueled by intricate Afghan tribal relationships and cultural codes. Before long, McCulloch said, it will be like the Marines were never there.

"I give it less than 12 months," he said.

A Marine sergeant who deployed to Afghanistan in 2012 as part of an embedded training team expressed faith in the Afghan troops' willingness and ability to fight the insurgency on their own, but said the U.S. forces were hopelessly overmatched when it came to effecting lasting change in a country beset by corruption and disarray. "How can 14 years fix 2,000 years?" he said.

Amid the pessimism and disappointment, former commanders of Marine forces in Afghanistan say that, while the future of Afghanistan is a mystery, the Marines have many reasons to be proud of their part in this long, hard war. Two things, specifically, they all agreed were certain: the Marines leave Afghanistan having achieved victory in their mission, and the Corps would never be the same for having served there.

Out of Afghanistan

Early in the morning on Oct. 26, the last 872 Marines remaining in Helmand province boarded C-130 jets and left for Kandahar Air Field, a brief stop on their way back to the United States. They left behind a few hundred million dollars worth of dusty desert tents and hard-shelled structures, all-terrain vehicles and an air strip. Little remained by way of monument to the tens of thousands of Marines who cycled through Camp Leatherneck since 2009, when President Obama ordered a surge of 30,000 troops into Afghanistan. The neighboring Nimroz and Farah provinces, which had seen hard-fought battles between Marines and the insurgency in previous years, had long since been turned back over to the Afghans, their bases dismantled or handed off.

The first Marine force had swept into Afghanistan just weeks after the Sept. 11, 2001, terrorist attacks on the World Trade Center buildings and Pentagon. Led by then-Brig. Gen. James Mattis, who would eventually become a four-star commander of U.S. Central Command, Task Force 58 was more than 1,000-strong, composed of the 15th Marine Expeditionary Unit, 26th MEU and other Navy and Marine Corps elements.

From ships at sea, the task force would move inland on CH-53s to establish Forward Operating Base Rhino, southwest of Kandahar in the Registan Desert. They also took control of the international airport in Kandahar, assisted with security at the U.S. embassy in Kabul, and conducted a variety of reconnaissance missions.

But while the Marine Corps was first on the ground in 2001, its work in Afghanistan would begin in earnest some seven years later when the 24th Marine Expeditionary Unit returned to Kandahar, then moved into the Taliban stronghold of Garmser in Helmand province, a little-populated hotbed for insurgent activity in the southern reaches of Afghanistan, where poppy farming fueled a thriving drug trade. Later the same year, 2nd Battalion, 7th Marines deployed to Helmand and Farah provinces, waging a pitched battle with insurgents from Now Zad to Delaram. When the surge hit its stride the following year, 11,000 Marines joined British troops operating in Helmand. As the surge troops established themselves in Helmand and southern Afghanistan, this region would become affectionately known as "Marine-istan."

"I think we understood going into Afghanistan, when we got that mission, it was really the two-fisted fighter," said Maj. Gen. Larry Nicholson, who as a one-star general in 2009 led the 10,000 troops who fell under Marine Expeditionary Brigade-Afghanistan. "We were going to go after the Taliban, but we were really going to go after the population."

To that end, Nicholson said, the work was complex.

"Where we went, we cleared. Where we cleared, we stayed. And where we stayed, we built," Nicholson said. "We were very determined to go to those population centers. It's a remote area, but those population centers, we worked very hard to get there and start building, not American trust, but [Afghan] trust in their government."

Marjah and Sangin

Despite the Marines' focus on civil affairs and the tenets of counterinsurgency, it became clear, said Nicholson, that they would have to aggressively pursue the insurgency deep into its own territory.

"We were reminded constantly, 'Yeah, the Marines are doing okay there [in Helmand]. We're impressed with what the British and Marines and Danes and Estonians are doing,' " Nicholson said. " 'But the enemy's in Marjah. When are you going to go there?' "

The urban region of Marjah, Nicholson said, had all but seceded from the rest of Helmand province. "They flew a Taliban flag," he said. "And we took that away from them."

Launched Feb. 13, 2010, Operation Moshtarak was led by 1,500 troops with 1st Battalion, 6th Marines, in conjunction with British, Afghan, and allied international troops. As the fighting stretched on for months, casualty rates climbed. Dozens of Marines would ultimately become casualties of the Marjah campaign. Progress in the region was slow as troops struggled to win the trust of local civilians they sought to help.

In May 2010, Army Gen. Stanley McChrystal, then the commander of all allied forces in Afghanistan, called Marjah a "bleeding ulcer" on the war effort. The region would ultimately become one of Helmand province's success stories, commanders who oversaw the effort there said, with Taliban activity quenched, schools and markets built and restored, and recently a peaceful presidential election.

But that would not take place, said Lt. Gen. Richard Mills, former two-star commander of Regional Command Southwest overseeing Helmand, until the Marines launched what would be their most difficult and costly Afghan offensive yet.

"We took the pressure off Marjah by going into Sangin," said Mills, now the commanding general of Marine Forces Reserve. "Sangin was critical to the enemy; it was an area the enemy was not going to give up. And the minute we went into Sangin, the pressure in Marjah was relieved."

Ultimately, Mills said, sending Marines into Sangin was the right decision. But nothing about it was easy.

During the 2010 assault on Sangin, 25 members of 3rd Battalion, 5th Marines, would lose their lives. The death toll in Sangin would ultimately rise to some 50 Marines and 100 British troops, who had held a presence in the Taliban hotbed and opium hub even before the Marines arrived. But when the Marines finally handed Sangin over to members of the 215th Corps this spring, it was on the heels of a relatively peaceful primary election. The insurgents, while still active, had been pushed to the fringes of the population centers, at least for the time being.

"That's the tough part of being a commander," Mills said. "You hope that the courage and bravery and dedication of those young Marines, that they can stick to it, and they did. But every casualty report is tough. They hurt, they hit home. As commander, you have to look at the strategic level of what you're trying to do."

Just a few years later, it was clear, Nicholson said, that these Afghanistan campaigns had an elite place in Marine Corps history.

"The iconic battles of this last decade have been ... Fallujah, Ramadi, Sangin, and Marjah," he said. "We fought like hell to take those areas."

Lessons from Afghanistan

The Marine Corps emerges from Afghanistan a changed force, due in part to the maturity and ingenuity gained from 13 years at war and in part from the passage of time.

Afghanistan saw the first major combat mission for the MV-22B Osprey tiltrotor aircraft, which now is an operational staple for the Marines in practically every theater imaginable. The Marines also benefited from the M142 High Mobility Artillery Rocket System, a truck-mounted long-range rocket they had used first in Anbar province, Iraq, but employed more heavily in Helmand province, deploying 400 of the powerful rounds by January 2013.

The war also saw the extended use of Marine Corps Forces Special Operations Command. MARSOC, which activated in 2006, matured throughout the war. The first deployment of a MARSOC company to Afghanistan in early 2007 was a disaster that resulted in as many as 19 civilian casualties and an order from the Army to return home early. But the rule-breaking and heedlessness that allegedly marked that first deployment was soon quelled.

To date, MARSOC troops have earned five Navy Crosses for heroism in Afghanistan, about a third of those awarded in that time period. Mills said MARSOC teams, operating in and around Helmand province, were a force multiplier for the Marines.

"They were operating kind of semi-independently," he said. "They were able to cover down on an area and backstop local security forces. They showed the enemy we have the ability to operate wherever and whenever we wanted to. And they did a tremendous job in combat."

As the mission in Afghanistan progressed, the Marines also prioritized cultural training and basic language classes, briefing Marines on how to relate to Afghan civilians. This included sit-down classes and having tooops attend "shuras" at mock-Afghan villages staffed by roleplayers.

Following a surge in deadly insider attacks targeting Marines in 2012 and 2013, the Corps implemented more advanced cultural and language integration for senior officers that drilled them on, among other things, the tenets of Afghan cultural norms. Marines in Afghanistan told Marine Corps Times earlier this year that they credited this training with defusing more potential insider attacks.

Nicholson said this cultural learning strategy had been critical to success in Marjah.

"We spent an inordinate amount of time trying to understand the human terrain in Marjah. We had Ph.D.s helping us try to understand that human dynamic," he said. "The trick now, frankly, is, that we don't lose it. All these skill sets that we've acquired, don't let them get away."

Nicholson is now pushing to rewrite the Marines' Small Wars Manual to incorporate the specific cultural lessons learned in Afghanistan.

The question of victory

The war in Helmand province has felt progressively less like a war since the Marines began transferring authority of various regions back to Afghan forces more than two years ago. In the last 12 months, even the Marines' advise-and-mentor mission has dwindled to nothing as officials encouraged the 215th Corps to operate independently. As troops stood guard outside Camp Leatherneck with few missions outside the base and little formal monitoring of what took place in the regions from which they'd departed, it was a strange way to end a war.

Brig. Gen. Daniel Yoo, the commander of RC-SW and Marine Expeditionary Brigade-Afghanistan during its last year in Helmand, said this lack of action had proven to be one of the hardest things for Marines in the war's final phase.

"We're very aggressive by nature," he said. "We look for solutions, there's no doubt about it."

What had helped to counter this frustration, he said, was observing the progress the 215th Corps had made since it was created from scratch in 2009 with a few handpicked leaders from the 205th Corps in Kandahar. The Marines helped Afghan troops create and man a regional corps battle school that equips new soldiers with a higher level of standardized training in Helmand, so the Corps doesn't have to send them to Kabul and risk losing them to the bigger city. They also trained Afghan tactical air controllers for the Corps' new fleet of Mi-17 and Mi-35 helicopters.

A visit to the battle school's firing range makes clear that some of the Afghans' military skills remain rudimentary, but Yoo points to Sangin as evidence of what their future could hold. Following the Marines' departure, an intense fighting season resulted in heavy ANA and civilian casualties. Afghan-held checkpoints changed hands, but Marine officials said the troops were ultimately able to regain them all. Yoo said a successful outcome in contested regions like Sangin might be a brokered peace or arranged coexistence between the government and Taliban and tribal factions.

"As long as the district centers are open, as long as the major lines of communication are open in order to provide services, and people can move from district center to district center, that to me is somewhat stable," Yoo said. "It's when, what we saw in the past when the insurgents ruled everything to include the local law, that's when I think it's probably a perspective that there's failure there."

Did the Marines achieve victory in their Helmand mission?

"Absolutely," Yoo said.

Like Yoo, Mills said time will prove the long-term effect of the Marines' efforts and the Afghan troops' ability to sustain the change. "I expect the insurgents to test the force that we left behind; I think that everybody expects that," he said. "My prediction is that will surge over the next fighting season, and that will be the ultimate decision. The next two or three years will be critical." He argued that accomplishments such as building schools, viewed by some Marines to be extraneous to the task of warfighting, were actually crucial to the success of Helmand province. "It showed that the insurgents could no longer threaten the people into doing what they wanted. That was an important metric on our success. Because the Taliban hated education."

Nicholson said he was cautiously optimistic about the future of Helmand though he said it was imperfect and a work in progress. He was proud, he said, of what the Marines had done. For the country of Afghanistan, he said, the proof of victory is in peace. "A country at peace with itself and its neighbors, able to provide for its own security, that kind of smells like victory to me," he said.

Mattis, the legendary Marine commander who led the invasion of Afghanistan, declined to speculate on the long-term effects of the Marines' work there, saying he had a variety of reasons for wanting to remain silent on the topic for now. But he offered a statement of appreciation for the work of the Marines nonetheless.

"Gen. Mattis might have said the Marines are no better friend and no worse enemy," he said, "but it was the lads in the infantry and the engineers who proved it beyond a doubt."