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Advanced Fire Combat with Modifiers

Mil 211

Sirs, it is assumed any officer reading this already knows how a Fire Combat Result is determined. If you do not please revisit your notes from MIL 210: Basic Fire Combat Results. If you learned anything from that lecture, I hope it’s that the math the game gives you is always correct when it comes to Fire Combat. The modifiers listed here all do exactly what they say they do.  


There is a great scene from the movie Gettysburg where the character of James Longstreet is sketching out the plan for Pickett’s Charge in the dirt of Seminary Ridge. The plan seems simple. Move ahead, oblique to the flank, and drive forward through the enemy line. In reality there would be numerous fences, structures, stone walls, and an elevation change to deal with – not to mention thousands of well-trained Yankees. In this game we call those – modifiers. And unless you want to end up like Pickett’s ill-fated charge did, you need to know all about these modifiers.


Hexside Modifiers

To take advantage of a Hexside Modifier you must be in position for one full turn within the hex. The modifier will then decrease the effectiveness of enemy Fire Combat by the modifier shown in the Parameter Data when that fire crosses the hexside which contains the modifier. In other words, a stone wall facing north won’t give you a modifier if the fire comes from the south. In the example below a unit is aligned behind a stone wall on the northern side of the hex. The red hexes represent the hexes which would fire at a disadvantage as a result and the blue ones which would fire “around” the stone wall from the flanks.


Hexside modifiers are your best friend on defense. Defensive hexside modifiers are stone walls, fences, creeks, streams, and embankments. Always check the Parameter Data in your specific scenario as the modifier percentages can often change from game to game. As an example – at Gettysburg there is no modifier for a position behind a stream or creek, while at Antietam there is. We will use Antietam’s Parameter Data for the purposes of this course. The Terrain Combat Modifiers are listed below with the Hexside-specific modifiers highlighted in the Parameter Data.


The only exception to this is the modifier for the “Cut” which actually increases the effectiveness of enemy Fire Combat by 50%. Cut’s are very rare and if you see them (usually around an unfinished railroad bank) you should avoid them at all costs.


A major advantage of hexside modifies to a defender is that they double as modifiers during both Fire Combat and Melee Combat. This means that the -40% modifier of a stone wall would apply to ranged Fire Combat as well as a Melee by the enemy over the hexside modifier.


Hexside modifiers are usually easily identifiable on the map. If you are unsure of the hexside modifier, or its precise location, you can always right-click on the Hex Information Box to see a diagram of the modifiers around the hex.




Hexside modifiers are the easiest of all the games defensive modifiers to take advantage of because of their abundance on the maps and their ready-made nature. Any good defensive line will utilize these as much as possible. Hexside modifiers may also be combined with other defensive modifiers to further enhance their usefulness. Try building a breastwork along a stone wall and you will see what I mean!

Terrain Modifiers

In our games there are eight different types of hexes. There are Forest, Rough, Orchard, Field, Marsh, Water, Clear, and Town hexes. Each comes with its own modifier for those occupying the hex when fired upon. The occupant does not need to establish residence in the hex for a full turn to enjoy the modifier of the hex during Fire Combat (as they do with hexside modifiers). Further, a terrain modifier may be combined with hexside modifiers to increase the overall modifier during Fire Combat (i.e. if a Forest hex had a hexside Fence – the defender would have a total -60% modifier). However, unlike hexside modifiers, the terrain hexes give no modifier bonuses during a Melee. Also, unlike hexside modifiers, a terrain hex gives you the modifier of the hex regardless of which side the enemy fire is coming from. The terrain modifiers are highlighted below:

Manmade Modifiers

Sometimes in life you just have to take things into your own hands and build your own modifiers – introducing breastworks and trenches. Other times the defenses are already set up in the form of abatis.



The most popular defensive structures built by players are breastworks. To build Breastworks, an infantry unit must be in Line formation, or a cavalry unit must be Dismounted. Use the "Make Entrenchments" option from the drop-down Command Menu on the top toolbar (or the Toggle Entrenchments button on the toolbar) to start construction. The unit will be described in its info box as making "Breastworks". Like hexside modifiers the modifier of breastworks only apply to the side of the hex where they are constructed. When a unit is fired upon or Meleed against across that side, then a combat modifier applies as given by Parameter Data (i.e. -30% for Antietam).


Breastworks may be combined with both hexside modifiers and terrain modifiers to better defend a hex against Fire Combat.


Q: Can you combine enough modifiers to make a position nearly impossible to take?


A: You bet your Jefferson Davis signed portrait you can! Let us take a unit and place it in a Forest hex. On one hexside there is both a breastwork and a stone wall. The math for this combination makes inflicting any losses in Fire Combat impossible. The modifier is -110%. I ran the test ten times and inflicted ZERO losses on the target unit. Maybe I needed bigger guns? Okay, so I equipped a 1000-man regiment with 1000 10” Columbiad Artillery pieces to fire. Oh, yes, you can do that in the editor in case you didn’t know. And the result is shown below.

Despite an absolutely insane 28000 Fire Value the defenders still suffered no losses! Take advantage of defensive hexsides and terrain!!! I cannot stress that enough and this proves it. By combining enough modifiers your men can become invincible!


But, don’t forget, they can still Melee or flank you. That same impregnable position giving the defenders a -110% modifier would give a Melee attacker only a -40% modifier (40% for a Stone Wall) and you might be driven back or routed from your bastion. Conversely, don’t be that fool that attacks areas of such strength! If an enemy has a position like the one I tested against you have to know when to move on and just find an open flank if possible.



Q: How long do breastworks take to build?


A: It’s a mystery. The Parameter Data for Gettysburg says that breastworks have a “Building 20%” statistic. Beyond that there is nothing. What does it mean? Darned if I know for sure. But I have done some testing just to find out. It always seems like building breastworks takes forever when you have just a few men building them but are completed faster when you have more men building them. But if the “Building 20%” means each unit has a 20% chance of completion then, theoretically, it shouldn’t matter if the unit building them is 50 men or 500 men. They should all complete around the same time, right? Wrong.


I put 100 units on a map. Ten units each with a strength of 1000, 900, 800 etc. down to 100 men. All began building breastworks at the same time. The larger units finished within just a few turns while the smaller units took much longer. So, it can’t be a straight up 20% chance of completion per unit.


My conclusion is that the statistic means that for every 100 men engaged in building breastworks they have a 20% chance of completion. This would account for the speed of larger stacks and slowness of smaller ones. It would also account for the randomness of completion even with units of the same size. A 1000-man stack would have a 20% chance ten times to complete breastworks during a turn. In my test the larger units (700 – 1000) all completed their breastworks within 5 turns. This seems to make the most sense. Can I prove it? No. But unless anyone has a better explanation, I am going with mine.


Bottom line, if you want breastworks built in a hurry you better use more men.



Unlike breastworks, which are basically a hexside modifier, a trench is, essentially, a terrain modifier. While breastworks apply only to the side of the hex they were built upon, a trench applies to the entire hex regardless of the direction of fire. This makes them extremely valuable in Fire Combat. To construct Trenches, an infantry unit must be in Column formation, or a cavalry unit must be Mounted. This makes the construction of trenches a highly risky action if you are unsure of the enemy’s location. Use the "Make Entrenchments" option from the drop-down Command Menu on the top toolbar (or the Toggle Entrenchments button on the toolbar) to start construction. The unit will show up described as Entrenching. For each hundred, or fraction of a hundred, men in a given hex Entrenching, 1 is added to the Trench Value in that hex per turn. When the Trench Value in the given hex reaches the Trench Construction value, the hex will become a Trench hex. In other words, if you have 400 men entrenching and the Trench Value is 20 it will take you five turns to finish the trench.


Units that move into a trench hex, from a non-trench hex (unless using a road and in column), are automatically Disrupted! If you are planning on going over to the offensive after defending your line be sure that you avoid crossing trench hexes which will cause you disruption. Just like other terrain modifier hexes, trenches do not protect you during a melee. But they are combinable with other hexside modifiers and terrain modifiers to further increase a positions strength. If you recall the example from above where we constructed breastworks along a stone wall inside of a Forest hex… you can also add trenches there!



A hex may contain Abatis in some scenarios. Abatises are defined in Wikipedia as “a field fortification consisting of an obstacle formed (in the modern era) of the branches of trees laid in a row, with the sharpened tops directed outwards, towards the enemy. The trees are usually interlaced or tied with wire.” These obstacles are frequently found in scenarios involving set defensive works around cities and forts.


Just like a terrain hex modifier an abatis affects the entire hex as opposed to a singular side like a hexside modifier would. But they serve a very different purpose than either breastworks or trenches. Whereas those defensive structures are meant to protect the occupant of the hex this one is meant to harm them. To begin with a unit moving into a hex containing abatis automatically becomes Disrupted unless it is using Road Movement. Second, the unit pays a movement penalty and suffers a fire modifier (usually 20%) when fired upon depending on the value of the Parameter Data. Abatis cannot be destroyed or constructed by the player during the game. Abatis are great at breaking up enemy advances and in slowing down any attack.  


Elevation Modifiers

The high ground! Military strategy since the dawn of time has been to take the high ground. Not only does it offer better visibility to see further but it also acts as a modifier against enemy Fire Combat and Melee Combat.


The target unit receives a defensive benefit when it is at a higher elevation than the firing unit. This benefit is normal for a single elevation change and is doubled for any elevation change of 2 increments or more. The actual value of this benefit can be found in the Parameter Data. As an example, using Antietam’s Parameter Data, this would be a -20% modifier if the targeted unit is at a higher elevation. That doubles to 40% for any elevation change of 2 increments or higher! Use the high ground!


Q: Is your offensive fire increased by being on the high ground?


A: Unfortunately, it is not. The enemy fire upon your lines will be reduced but your own shot and shells will still have their regular effect.

Firing Unit Modifiers


1) Units which fire Offensive Fire after movement in the current Turn do so at half effectiveness.


Of all the Offensive Fire Modifier rules in the game this is the most detrimental to any attacker. This adds a -50% modifier to your offensive fire output. When coupled with other types of modifiers it can be a real challenge to overcome.


2) Disrupted units fire at 50% effectiveness.


Any attacker will inevitably see the disruption of numerous units as they engage the enemy at close range. These units will be firing at 50% effectiveness as a result. And what happens if you move a unit first, and then fire while you are Disrupted? The penalties combine to reduce them to just 25% effectiveness.


3) Units that are constructing Breastworks or Trenches fire at 50% effectiveness.


It is wise to be sure that the battle won’t unexpectedly erupt around you before you begin to build defensive emplacements.


4) If the Firing Quality Modifier Optional Rule is in effect, a unit has 10% added to its fire value if it has a Quality of A or B, and 10% is subtracted from its fire value if it has a Quality of E or lower.


This rule is one of the more used rules in the Club for good reason. It treats veterans and greenhorns differently in battle and allows that there would variations in the fire combat from each type of unit.


5) Units with Medium Fatigue suffer a 10% reduction of their fire value, units with High Fatigue suffer a 20% reduction, units with Maximum Fatigue suffer a 40% reduction.


Once more this underlines the importance of keeping your men fresh and rotating out units with increased fatigue.


6) Dismounted Cavalry fires at ¾ effectiveness to account for the horse holders.


This is the only rule on this list that effects only Cavalry.

Target Fire Modifiers


1) Target units which have not moved during their turn get a defensive benefit from certain hexsides. The actual benefit is determined by Parameter Data.


You will not receive any benefit from a hexside modifier until you have spent a full turn in the hex. This is different than terrain modifiers which are applicable right away.


2) Target units may get a defensive benefit from the terrain of the hex they are in. The benefit is shown in the Terrain Info box of the Unit List.


Use terrain modifiers whenever possible but, remember, they do not help you against a melee, on in Fire Combat.


3) The target unit receives a defensive benefit when it is at a higher elevation than the firing unit. This benefit is normal for a single elevation change and is doubled for any elevation change of 2 increments or more. The actual value of this benefit can be found in the Parameter Data.


As mentioned earlier, the high ground will give you a bonus when fired upon.


4) A unit in Line formation that is fired upon by a firing unit that it is not facing is subject to an Enfilade fire modifier. The value of this modifier is in the Parameter Data.


Being fired upon from your flank or from the rear will cause increased losses. Another major thing, not mentioned above, is that being fired upon in enfilade will cause a subtraction of 2 points from any subsequent morale check you take. 


5) The Enfilade fire modifier also applies to any fire against Infantry in Column or Limbered Artillery.


Firing at an Infantry Unit in Column or a Limbered Artillery Unit, from any direction at all, will give you a 40% modifier.


6) When the target unit is in Abatis, behind Breastworks, or in a Trench Hex, a modifier determined by Parameter Data is applied.


Already discussed but worth mentioning again.


7) Fire against a Mounted Cavalry unit may be modified by the Cavalry Fire Modifier Parameter Data value.


At Antietam, for instance, there is a 40% modifier when firing against Mounted Cavalry. Do not make the mistake of being caught Mounted in the middle of an infantrymen’s fight.

Density Fire Modifier Optional Rule


This Optional Rule is so important I decided to give it a separate section all by itself. If you read the Optional Rules section this may come as a refresher. The Optional Density Fire Modifier Rule is never explained anywhere in the User’s Guide but rather in the Campaign Editor’s Guide. It explains that a hex 2/3 filled to the maximum number of allowed men (667 if a hex holds a 1000) creates a modifier which is applied to the hex as a penalty for overstacking the area. But beyond that we have no clue what it means. Here is the lowdown.


For a hex with a strength of 700 men (whether in one regiment or multiple regiments it doesn’t matter) the game gives a 5% modifier to any unit firing into those men. Whether it is Offensive Fire hitting the 700 men or a Defensive Fire it does not matter. A 500-man Average Quality unit firing at range 1 will have a Standard Fire Value of 2000 against a hex filled with 1 – 666 men. But after that target hex fills up to 667+ men he begins to gain a modifier. If there were 750 men in the hex the modifier would rise accordingly to 12.5%. An 800-man hex would suffer a 20% modifier. A 900-man hex would have a 35% modifier while a fully packed 1,000-man hex would suffer a 50% modifier when fired upon.


Obviously, the game does this to try and disincentivize players from building larger stacks by increasing their casualties accordingly. From a historical standpoint it can also be, correctly, argued that the more densely packed men are the more likely casualties would become as a result. This Optional Rule is a greatly misunderstood and ignored rule, I think, by many because it is never explained in the rules and its implications are not deemed important enough to know. Aim for the larger stacks when they present themselves and watch the enemy fall at a faster and heavier rate. 

What else the Game Rules Overlook!


Is it possible the Game Rules failed to tell us everything?! Yes, it is. Let’s review a few common questions and then see if we can figure out the answers using a few tests.


Q: When I fire multiple units at once what happens?


A: On the surface this seems fairly obvious. Let’s take four 250-man Average Quality regiments with no other variables in place. The following equation will give us the answer we are looking for. The odds would be 250 men with Rifles (effectiveness 4 at a range 1) times 4 for the four units involved. This would create a Standard Fire Value of 4000 (250 x 4 x 4). The Low End Combat Result would be 20 (= 5 x 4000 / 1000) and the High End Combat Result would be 100 (= 25 x 4000 / 1000). With no modifiers in place the computer would choose a value between 20 and 100 as a final combat result. The median number here is 60 so let us run the test twenty times and see if 60 is the average result. The final average for casualties inflicted was 58.5 during the tests. The game simply takes the combined Fire Value for each regiment, adds them up, applies modifiers, and rolls the die for a result.




Q: What if one of the units firing is Disrupted? Does the -50% modifier apply to all the units?


A: Good question. When conducting a Melee if one unit is at a disadvantage (by being lower quality or crossing a hexside modifier) than all the units in the Melee share that modifier. But with a Fire Combat that is NOT the case. In a Fire Combat only that particular regiment’s effectiveness is diminished while the other units fire with their own set of modifiers. Let us do the Math to show you what I mean. We can run the test here by placing the same four 250-man regiments back on the map and making two of them Disrupted. The Math for this will then work out as such. The odds would be 250 men with Rifles (effectiveness 4 at a range 1) times 4 for the four units involved. This would create a Standard Fire Value of 4000 (250 x 4 x 4). Two units are Disrupted though so they will have their Fire Values cut in half. The four Fire Values would then be 1000 1000 500 500 add these up then for the combined Fire Value. The Low End Combat Result would be 15 (= 5 x 3000 / 1000) and the High End Combat Result would be 75 (= 25 x 3000 / 1000). The median number here is 45. After running the test twenty times the average casualties were 46.8 for the target regiments.

If you can think of any other questions about Fire Combat be sure to let us know and we will answer them as best we can. For more information on Artillery Combat and Cavalry Combat be sure to check the manuals on those branches.

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