Then-Army Gen. David Petraeus (left) and Marine Corps Gen. John Allen in August, 2011. Chip Somodevilla/Getty Images hide caption

itoggle caption Chip Somodevilla/Getty Images

David Petraeus, then-CIA director, testifies before the Senate Intelligence Committee in January. Petraeus resigned Friday after acknowledging an extramarital affair. Karen Bleier/AFP/Getty Images hide caption

itoggle caption Karen Bleier/AFP/Getty Images

Then-Gen. David Petraeus in mid-2011, just before he became CIA director. Barbara Sax/AFP/Getty Images hide caption

itoggle caption Barbara Sax/AFP/Getty Images

David Petraeus, while he was the top commander of U.S. and coalition forces in Afghanistan, and Paula Broadwell in July 2011. He resigned from his post as CIA director because of an extramarital affair they had. ISAF/Reuters /Landov hide caption

itoggle caption ISAF/Reuters /Landov