"In the months leading up to the war on Iraq, battles over doctrine and tactics were still raging within the military. The struggle was primarily between the more cautious "Clinton generals" in the Army, who advocated a methodical invasion with a robust force of several hundred thousand, and Secretary of Defense Donald Rumsfeld and his acolytes, who argued for a much smaller invasion force- one that would rely on speed and mobility more than on firepower. Rumsfeld's interest in "maneuver warfare," as the doctrine that emphasizes mobility over firepower is called, predated invasion planning for Iraq. Ever since becoming Secretary of Defense, Rumsfeld had been pushing for his vision of a stripped-down, more mobile military force on the Pentagon as part of a sweeping transformation plan. Mattis and the Marine Corps had been moving in that direction for nearly a decade. The Iraq campaign would showcase the Marines' role in Iraq as a rush. While the U.S. Army- all-powerful, slow-moving and cautious- planned its methodical, logistically robust movement up a broad, desert highway, Mattis prepared the Marines for an entirely different campaign. After seizing southern oil facilities within the first forty-eight hours of the war, Mattis planned to immediately send First Recon and a force of some 6,000 Marines into a violent assault through Iraq's Fertile Crescent. Their mission would be to seize the most treacherous route to Baghdad- the roughly 185-kilometer-long, canal-laced urban and agricultural corridor from Nasiriyah to Al Kut."