The term Commander's Intent is taken from the book Made to Stick by the brothers Heath, p.26.
It refers to the fact that no amount of planning will survive the encounter with reality. One can plan only to be ready for contingencies. Unexpected events, conditions, and contingencies abound in most real situations. Therefore, the actor can only adapt. You can lose the ability to execute the original plan, but you never lose the responsibility of executing the intent. Carrying out the original intent requires adaptability and creativity.