“It is definitely a strange place,” said Capt. Brian Neese, an Air Force physician. “I’ve asked the Civil Affairs guy if there is anything that I can do off base, and there just isn’t anything for me to do. What kills is not the difficulty of the job but the monotony.”

At the height of the war, more than 300 bases were scattered across Iraq. Over the next few months, Americans hope to be at six huge bases, with 13 others being used for staging and preparing for a complete withdrawal.

The first people you encounter when driving up to an American base are not actually American. They are usually Ugandans, employed by a private security company, Triple Canopy, and those at Balad had enough authority to delay for five hours an American Air Force captain escorting an American reporter onto the base.

Image Joint Base Balad is spread over 6,300 acres. Credit... The New York Times

The Ugandans make up only one nationality of a diverse group of workers from developing nations who sustain life on the F.O.B.’s for American soldiers. The largest contingents come from the Philippines, Bangladesh and India. They live apart from both Western contractors and soldiers on base, interacting with them only as much as their jobs demand.

“Everyone stays pretty much separate,” said Mila, the massage therapist, whose last name could not be used out of security concerns. She has been in Iraq a year, but she said other workers had been here as long as six years, some never taking a break to go home. “You miss nature, trees and grass,” she said.

The base has two power plants, and two water treatment plants that purify 1.9 million gallons of water a day for showers and other uses. The water the soldiers drink comes from yet another plant, run by a bottling company, which provides seven million bottles of water a month for those on base.