Douglas A. "Doug" Macgregor is a retired Army colonel, decorated in combat and an advisor on planning, military transformation and the broader aspects of revolutions in military affairs until his retirement 2004; his final assignment was Senior Military Fellow, Institute of National Strategic Studies (INSS), at the National Defense University. Macgregor is one of a number of colonels who were respected conceptual thinkers, but either were too controversial, or not seen as having the management and political skills, to make general officer rank. He regarded Secretary of Defense Donald Rumsfeld, a proponent of transformation, as an ally. 
He was operations officer of the 2nd Squadron of the 2nd Armored Cavalry Regiment in the Battle of 73 Easting.
In his book Breaking the Phalanx, he described the principles used in the restructuring of the United States Army from a division to a brigade structure.  Military analyst and author, LTC (ret.) Ralph Peters said that while Macgregor did not get everything right "He articulated where we need to go, towards smaller, more mobile, more balanced forces. It's clearly the wave of the future to anyone who's served, who's been out there, and is thinking about these issues honestly and isn't in the pay of a defense contractor. Doug MacGregor was a hero. He didn't have all the answers, but boy, he fired up the right questions."
Macgregor himself argues that no single-service approach, such as the brigade restructuring of the Army, can cause true transformation. It must be joint among all the services; they must have a common operational picture. 
Iraq War planning
Art Cerebrowski, a retired admiral and Rumsfeld's head of transferormation planning, introduced Macgregor to Newt Gingrich. Gingrich asked Macgregor to prepare a briefing, which would be given to Rumsfeld, that went against the conventional wisdom that large forces would be needed to defeat Saddam.  Macgregor geve the briefing to Gingrich on December 31, 2001. It advocated a quick strike into Baghdad by three brigade-sized forces, followed by 15,000 light infantry forces to maintain order.
Macgregor was sent to brief GEN Tommy Franks, commanding United States Central Command, on January 12, 2002. He first presented to one of Franks' planners, COL Mike Fitzgerald, who thought the plan's logistics were not worked out, and did not include artillery. Fitzgerald, an artilleryman, walked out.
After Macgregor briefed Franks, Franks responded, "Attack from a cold start. I agree. Straight at Baghdad. Small and fast. I agree. Simultaneous air and ground. Probably, but not sure yet." After his return to Washington, Macgregor decided that Franks had given him a polite reception as a courtesy to Rumsfeld; Macgregor wrote a memo of the meeting, which Gingrich forwarded to Dick Cheney; Macgregor continued advising through Gingrich, and a friend of a friend of White House Chief of Staff Andy Card.
Franks' planner, MG Gene Renuart, tried to explain to Rumsfeld that the forces were too light. During the approach to Baghdad, when Rumsfeld questioned a pause for logistics to catch up with the forces under LTG David McKiernan, Macgregor wrote another memo, which went to Rumsfeld via Gingrich, that the Army was risk-averse about its logistics; "the soldiers are out to win and will win if allowed to, but they need momentum on their side." Rumsfeld thanked Gingrich for it. .
Later, after the fall of Baghdad, Gingrich reemphasized to Rumsfeld that Macgregor had emphasized an armored force; the Office of the Secretary of Defense was overemphasizing special operations forces, perhaps based on their success in the different environment of the Afghanistan War (2001-).
A graduate of West Point, he holds a master's in comparative politics and a doctorate in international relations from the University of Virginia.
- Michael R. Gordon, Bernard E. Trainor (2006), COBRA II: the inside story of the invasion and occupation of Iraq, Pantheon, ISBN 0375422625, p. 8}}
- Doug Macgregor (1997), Breaking the Phalanx: A New Design for Landpower in the 21st Century, Praeger Paperback, ISBN 0275957942
- "Interview: Ralph Peters", Frontline, Public Broadcasting Service
- Douglas A. Macgregor (Autumn 2000), "Transformation and the Illusion of Change", National Security Studies Quarterly
- COBRA II, pp. 33-35
- COBRA II, p. 318
- COBRA II, p. 100