I could only find the several nixed after Libya, and at least one more. I think there has been more, but am not sure ——— http://www.freerepublic.com/focus/bloggers/2995277/posts
Gen. Carter Ham, on October 18, 2012
Adm. Charles Gaouette, on October 27, 2012
Gen. David Petraeus, on November 9, 2012
Gen. John Allen, on November 13, 2012
Cmdr of CENTCOM James Mattis March, 2013
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I feel like this is more, but I am not sure.