Forward Operating Base (FOB) Caldwell was a U.S. military installation located in northern Iraq. It was named in honor of Specialist Nathaniel A. Caldwell, who died in Iraq in 2003.

Situated in the Diyala province near the Iran-Iraq border, FOB Caldwell was strategically positioned for operations in a region marked by a complex mix of ethnic groups and ongoing tensions. During the Iraq War, Diyala was a significant area of operations against insurgent groups, and FOB Caldwell played a critical role in these efforts.

As a Forward Operating Base, FOB Caldwell functioned as a secured, advanced military base supporting tactical operations during the war. The base was typically used for troop housing, tactical operations, and logistical support. It offered a relatively secure location from which to conduct and coordinate operations, including counterinsurgency missions, patrols, and training of local forces.

The facilities at FOB Caldwell included housing units for troops, dining facilities, operations centers, and other support infrastructure necessary for a functioning military base. Despite its remote location, the base provided services for the personnel stationed there, maintaining morale and readiness during their deployment.

Like many U.S. military installations in Iraq, FOB Caldwell was eventually handed over to the Iraqi government as part of the U.S. strategy of transitioning security responsibilities to Iraqi forces. The future of these bases, including FOB Caldwell, is tied to the ongoing political and security developments in Iraq.