Is this a suggested rules change - page 18 under heading Command Performance - "Brigade commanders move after all units in their brigade have been moved,". In the Turn Sequence on page 17 and under the heading Commanding General on page 12 it seems clear that the Commanding General is moved first at the start of the turn in order to tactically boost the Command Performance roll of a particular command. It seems to me that Brigade Commanders should not move until the end of the movement phase - because that way if any units retreat during Fire or Melee Reaction it is more likely that command range may have been disrupted - which is the point of having a command range I would think? Moving at the beginning of the turn allows the Brigade General to optimise his location despite all the chaos that may have occurred in the previous turn's combat.
We also found that positioning the Commanding General is actually quite difficult to optimise - it is easy to pick a spot where he will boost a Command Performance roll but having him in the best spot to boost the morale of retreated units is a lot harder to foresee - which is probably as it should be - means you must decide if boosting Command or Rallying units is your top priority each turn.