Military
Commissioned as a second lieutenant in May 1982, Mansoor served in a variety of command and staff assignments, including postings with the 3rd Armored Cavalry Regiment at Fort Bliss, Texas; the 11th Armored Cavalry Regiment in Bad Hersfeld and Fulda, Germany; and the 11th Armored Cavalry Regiment (Opposing Forces) at the National Training Center at Fort Irwin, California. He commanded the 1st Squadron, 10th Cavalry and served as operations officer (G-3) of the 4th Infantry Division (Mechanized) at Fort Hood, Texas. In 1993–1995 he was a military history instructor at the U.S. Military Academy. He later served on the Joint Staff as the special assistant to the Director for Strategic Plans and Policy (J-5) in the United States Department of Defense, during a period that included the Bosnian peace support operation, Operation Desert Fox, and the Kosovo War. From July 2003 to July 2005 Mansoor commanded the 1st Brigade, 1st Armored Division, which was deployed in Iraq from May 2003 to July 2004.[3]
In 2005 Mansoor became a senior military fellow at the Council on Foreign Relations in New York.[4] He then served as the founding director of the U.S. Army/Marine Corps Counterinsurgency Center at Fort Leavenworth, Kansas. There he helped to edit FM 3-24 Counterinsurgency, published in December 2006, which was used to reshape the conduct of the Iraq War. In the fall of 2006 he served on the so-called "Council of Colonels," a task force of senior officers created by the Joint Chiefs of Staff that reexamined the strategy for the war in Iraq.[5] During its deliberations, Mansoor advocated sending additional troops to Iraq as part of the strategy eventually known as "the Surge," albeit at a lower strength level than the option preferred by then-Colonel H. R. McMaster, another member of the Council. Mansoor termed his strategy preference the "Go Long" option.[6] At the time he formed a minority among the Council of Colonels, most of whom opposed the idea of a troop surge.[7]
Mansoor's military career culminated with his assignment as the executive officer to General David Petraeus, Commanding General of Multi-National Force – Iraq, during the period of the Surge in 2007–2008. Military analyst Tom Ricks, author of The Gamble (2009), describes Mansoor as one of the two "most important advisers to Petraeus."[8] Mansoor retired with the rank of colonel in August 2008.[2]