Fighting for isolated mountain valleys like this one, even if they are hide-outs for clusters of Taliban, was no longer sustainable. It did more to spawn insurgents than defeat them. Better to put those soldiers in cities and towns where they could protect people and help them connect to the Afghan government, he reasoned.

“There’s never a perfect answer,” General McChrystal said as he visited this outpost on April 8 for a briefing as the withdrawal began. “I care deeply about everybody who has been hurt here, but I can’t do anything about it. I can do something about people who might be hurt in the future.

“The battle changes, the war changes,” he added. “If you don’t understand the dynamics, you have no chance of getting it right. We’ve been slower here than I would have liked.”

Forty-two Americans died fighting in the Korangal Valley and hundreds were wounded, according to the military. Most died in the period from 2006 to 2009. Many Afghan soldiers died as well, and in larger numbers, since they had poorer equipment. In a war characterized by small, brutal battles, the Korangal had more than its share, and its abandonment has left soldiers who fought there confronting confusion, anger and pain.

Image Forty two American service men died fighting in the Korangal Valley and hundreds were wounded in the place that came to be called the Valley of Death. Credit... Christoph Bangert for The New York Times

“It hurts,” said Specialist Robert Soto of Company B, First Battalion, 26th Infantry, who spent 12 months in the valley from 2008 to 2009. “It hurts on a level that — three units from the Army, we all did what we did up there. And we all lost men. We all sacrificed. I was 18 years old when I got there. I really would not have expected to go through what we went through at that age.”