So on Saturday, the Marines returned to Helmand with a force of 300; roughly half of them had previously served in the province. The same flag that was lowered in 2014 and then stored at the Pentagon office of the commandant of the Marine Corps was raised again at the 6,500-acre Camp Shorab, which the Marines will be sharing with the Afghan Army’s struggling 215th Maiwand Corps.

The Marines’ new mission is a difficult one: to assist and train Afghan soldiers and police to defend the provincial capital. The Taliban control seven of the province’s 14 districts and are encroaching on five others. The government fully controls just two, local officials say.

“It’s kind of disheartening — the sacrifices you and your Marines made, and to see it go back to where it was,” said Gunnery Sgt. Ronnie C. Mills, of Kentucky, who is on his second tour of Helmand after serving three tours in Iraq.

During his previous stint in Helmand, Sergeant Mills served in Marja, which was the scene of one of the biggest battles in 2010 after President Barack Obama ordered a troop surge to break the Taliban’s momentum. By the end of his tour in July 2011, Sergeant Mills said, the Marja district was “safe enough to walk down the road, to go to the bazaars.”