The next step in the estimate is the natural one of comparing the commander's retained courses of action with those of the enemy which have been retained for further study. This process consists of executing, in imagination, the plan contained in each of the commander's courses of action, against that in each of the enemy's. One method is for the Commander to take the initiative with each of his plans and mentally to push it through with vigor. By this procedure, he concentrates his thought on the effect to be produced, on the changed situation which that effect will bring about for the enemy, on the modification in the enemy's effort which will be caused, on the resulting obstacles which these modifications will create, and on the provisions which will have to be made to overcome the obstacles. It will at once be apparent that the commander may have to re-estimate the enemy situation during this analysis. Such necessity arises because of the changes made by his own course of action upon the enemy situation. The commander will desire to reach a studied conclusion as to what counter action the enemy may take when the nature of the planned action against him becomes evident. This re-estimate of the situation may be brief, as it is an adjustment of factors which are familiar through previous examination. Sometimes the re-estimate will have been made mentally, before reaching this point, and adjustments may already have been made in the written estimate, in anticipation of this contingency. Sometimes the commander may find it desirable, after reaching this point, to re-write, at least in part, his original enemy estimate (Section III). The particular procedure adopted is unimportant; the important feature is to recognize that such a re-estimate process is normal, and especially so with reference to this portion of the Estimate. The foregoing discussion illustrates the point that an examination into enemy capabilities is not complete if the commander puts himself in the enemy's place merely for the purpose of estimating the original situation from the enemy viewpoint. In addition, the commander examines each of the enemy's modified problems which the changed situation, created by the execution of the commander's plan, has superimposed upon the enemy's original problem. Thus only can the commander analyze the various ways whereby the enemy may oppose his own proposed courses of action. Thus only may sound conclusion later be reached, in the next subsection of the estimate, as to what course of action, or combination of courses, is the best.