Retired Col. Peter Mansoor, the executive officer to Gen. David Petraeus during the Iraq War surge and the author of a new book on the subject, is doing a Reddit AMA (Ask Me Anything) today. He answered a question that I asked.

Question: Your book Surge has harsh words for Secretary of Defense Donald Rumsfeld, stating that he "rightly" offered his resignation after the Abu Ghraib scandal and President Bush was wrong not to accept it. You write that Rumsfeld "demanded a war plan for Iraq predicated on the best-case scenario ... then refused to admit that his assumptions were wrong," which is a disastrous trait for a wartime leader. What are the biggest lessons future Pentagon leaders should learn to avoid being another Rumsfeld?

Mansoor: Senior leaders must be willing to listen. Rumsfeld thinks he was open to criticism, but he was not. If a leader cannot listen to contrary opinions and make informed decisions based on a full range of views, then he/she courts disaster -- as Rumsfeld did in Iraq.

Abu Ghraib was a moral failing of the U.S. military that should have resulted in the resignation of the Secretary of Defense. President Bush was faithful to his subordinates to a fault. He should have let Rumsfeld go in the spring of 2004 and put different leadership in place in the Pentagon.

-- Rogers Cadenhead