In 2005, President Bush articulated a national strategy for Iraq that hinged on successfully advising Iraqi security forces. "As Iraqis stand up, we will stand down," he said. The critical piece of this strategy was the adviser capability itself. Although the military's special operations community had long nurtured the capability to conduct "foreign internal defense," the Army and Marine Corps had largely marginalized this capability by the time of the Iraq war, disdaining it in favor of conventional combat operations. To achieve the president's vision for Iraq, the Army and Marines would need to build this capability from scratch, tearing...