Freeman's research of Lee was exhaustive. He evaluated and cataloged every item about Lee, and he reviewed records at West Point and the War Department and material in private collections. In narrating the general's Civil War years, he used what came to be known as the "fog of war" technique, providing readers only the limited information that Lee himself had at a given moment. That helped convey the confusion of war that Lee experienced as well as the processes by which Lee grappled with problems and made decisions.