Gen. Stanley McChrystal during a retirement ceremony in 2010. His comments in a Rolling Stone interview helped lead to his resignation. Brendan Smialowski/Getty Images hide caption

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Chuck Hagel, President Obama's nominee for defense secretary, testifies before the Senate Armed Services Committee during his confirmation hearing on Jan. 31. Susan Walsh/AP hide caption

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Gen. David Petraeus is the subject of The Insurgents: David Petraeus and the Plot to Change the American Way of War, a new book by Fred Kaplan. Shah Marai/AFP/Getty Images hide caption

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President Obama nominates former Sen. Chuck Hagel, R-Neb., to be defense secretary Monday at the White House. Mark Wilson/Getty Images hide caption

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Marilyn Gonzalez (left) and her daughter, Jessica Pedraza, at their base in Kuwait in 2010. Courtesy of Jessica Pedraza hide caption

itoggle caption Courtesy of Jessica Pedraza