The U.S. Marines in the country's south face the toughest fight, and the worst conditions, reports CBS News chief foreign affairs correspondent Lara Logan. They're surrounded by hard-core Taliban fighters in Helmand province, and the local people are often hostile - but sometimes war can deliver the unexpected.
For Marine Sgt. Anthony Matthews, the unexpected came in the form of a kiss on the hand from an Afghan child as he taught the youngster a handshake.
Matthews, a father of two, can't resist reaching across the cultural divide - trying to pass on a few American traditions - even here in the most violent part of Afghanistan.
"When you see people that can't help themselves and you can provide them with just a little security, it's worth doing it, and that's the thing about it," said Matthews.
In Afghanistan, that means something different every day. Recently, Sgt. Matthews and the Marines of Echo company used a canal as a secret approach into a Taliban-held village.
After an hour in the water, Marine engineers came scrambling back; they'd found a series of roadside bombs.
It took five more hours of waiting in the water before the bombs were destroyed.
Most days, they have to force their way through thick cornfields because the ground they patrol is so heavily mined with roadside bombs.
Getting through these cornfields is hard because the ground is uneven and it's full of mud. The humidity is stifling and it's hard to breathe, but it's great for cover.
Back at the base, there's nowhere to shower, no way to get comfortable. It's blistering hot and filthy dirty. Marines sleep wherever they can. They haven't washed for months.
"As you can see, just living out in the dirt, that's never good. The shower situation, the bathroom situation... going out every day, getting shot at, walking through the mud... you're never dry you're always wet," said Matthews, "just stuff like that."
What makes it bearable? When the mail truck finally arrives with letters from home.
"It's a struggle. You worry about your Marines here, you worry about family at home, it's hard trying to keep your head in the game," said Matthews. "Try to keep your mind off of home as much as possible here."
Many of these Marines are on their third or fourth deployments, and a lot of them have small children and young wives at home. But you really don't hear them complaining. That's a big part of the Marine culture.