What is the theme in Chain of Command: The Road from 9/11 to Abu Ghraib by Seymour Hersh?

Chain of Command is the main theme of the book. Working in a chain of command means you take responsibility for your actions and you expect your superior to take responsibility for his. There is accountability at all levels. Mistakes caused by lack of direction by a commander should be reason to question the ability of the commander, not the subordinate. Harry Truman used the phrase "the buck stops here" to describe his ultimate responsibility as President. Issues arise when commanders of low ethics ask subordinates to assume blame when given no proper direction.