Optional Rule Guide Manual defensive fire

[krmiller]

Without Manual Defensive Fire turned on you play in what is often called Turn Mode, you can move, fire and melee anytime during your turn.  This can lead to very ahistorical outcomes where a player can move units from the back into position, shoot or melee an opposing unit out of position then move through the hole created and surround other units, a blitzkrieg type attack.
The other big problem is all defensive fire in Turn Mode is done at 50% strength in addition to any other modifiers that may be in effect, such as Terrain, Disruption or Fatigue and the chance of units firing is random and units often do not fire at all while the enemy moves up and shoots.  This reduces the chance of disrupting attacking units.  The big difference between Napoleonic and ACW warfare was the effectiveness of defensive fire in breaking up attacks and this is more difficult to do in Turn Mode.

Using Manual Defensive Fire sets the game to play in what some call Phase Mode.
During Phase Mode Defensive Fire, whether handled using the Automatic Defensive Fire option or by the players using two Email files per turn, all units' fire is calculated at Full Strength prior to applying other modifiers, unlike the 50% reduction used in Turn Mode Defensive Fire.  Also all defending units that are eligible will fire under ADF unless the player's range settings prevent it.  Firing at full effectiveness increases the power of the defense and the defender gets to fire first giving him the opportunity to Disrupt the attacking units before they can fire reducing their effectiveness and preventing melee.

If you use both MDF and ADF and play in phases it still only requires one email by each player to complete a pbem turn, players 1 moves, AI handles defensive fire, player 1 shoots, melees and sends file to player 2.
If you elect to do the defensive fire phase manually it will take two emails to complete a turn.  Player 1 moves, sends file to player 2, he shoots, sends file back, player 1 shoots and melees, rinse and repeat.

If you don't use MDF and use Turn Mode I still suggest using ADF, it will have no effect on the AI controlled defensive fire during the opponents turn but will allow you to set ranges for when units will check to see if they fire using the Adjust Auto Defensive Fire option under the AI menu.  This can reduce the ammo wasted by the AI firing guns at long range where they do little damage and reduce the risk of infantry running low on ammo at such shots.