On the return of the division headquarters and 1st Brigade, the 10th Mountain Division began the process of transformation into a modular division.
On 16 September 2004, the division headquarters finished its transformation, adding the 10th Mountain Division Special Troops Battalion.
The 1st Brigade became the 1st Brigade Combat Team, while the 3rd Brigade Combat Team, 10th Mountain Division was activated for the first time.
In January 2005, the 4th Brigade Combat Team, 10th Mountain Division was activated at Fort Polk, Louisiana.
2nd Brigade Combat Team would not be transformed until September 2005, pending a deployment to Iraq.

In late 2004, 2nd Brigade Combat Team was deployed to Iraq supporting Operation Iraqi Freedom.
The 2nd Brigade Combat Team undertook combat operations in western Baghdad, an area of responsibility which included Abu Ghraib, Mansour, and Route Irish.
It returned to the US in late 2005.
Around that time, the 1st Brigade Combat Team deployed back to Iraq, staying in the country until 2006.
On the return of the division headquarters and 1st Brigade, the 10th Mountain Division began the process of transformation into a modular division. On 16 September 2004, the division headquarters finished its transformation, adding the 10th Mountain Division Special Troops Battalion. The 1st Brigade became the 1st Brigade Combat Team, while the 3rd Brigade Combat Team, 10th Mountain Division was activated for the first time. In January 2005, the 4th Brigade Combat Team, 10th Mountain Division was activated at Fort Polk, Louisiana. 2nd Brigade Combat Team would not be transformed until September 2005, pending a deployment to Iraq.
In late 2004, 2nd Brigade Combat Team was deployed to Iraq supporting Operation Iraqi Freedom. The 2nd Brigade Combat Team undertook combat operations in western Baghdad, an area of responsibility which included Abu Ghraib, Mansour, and Route Irish. It returned to the US in late 2005. Around that time, the 1st Brigade Combat Team deployed back to Iraq, staying in the country until 2006.
10th Mountain Division