Petraeus, who was McChrystal's boss as head of U.S. Central Command, is among the few seasoned war generals believed to be able to step into the job without disrupting the U.S. war effort.
In his current role role, Petraeus oversees military operations across the Middle East and managed both the war in Iraq and Afghanistan.
The shakeup comes as the American public questions whether the war can be won, and if it is worth fighting.
A White House official says Petraeus steps down as head of of CentCom in order to head U.S. forces in Afghanistan.
Petraeus In Brief:
AGE-BIRTH DATE - 57; Nov. 7, 1952.
EXPERIENCE - Commander, U.S. Central Command, Sept. 2008-present; commanding general of the Multi-National Force in Iraq, 2007-2008; commanding general of the U.S. Army Combined Arms Center at Fort Leavenworth, Kan., 2005-07; first commander of the Multi-National Security Transition Command in Iraq, 2004-05; commanded NATO training mission in Iraq, 2004-05; various positions, including commander of the 101st Airborne Division (Air Assault), assistant chief of staff for operations of the NATO Stabilization Force and deputy commander of the U.S. Joint Interagency Counter-Terrorism Task Force in Bosnia.
EDUCATION - Bachelor's degree, U.S. Military Academy, 1974; master's degree, Princeton University, 1985; doctoral degree, Princeton University, 1987.
FAMILY - Wife, Holly; two children.
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CBSNews.com Special Report: Afghanistan