[SIZE="4"]AACW Frontage Primer[/size]
By Major Tom
In military terminology, "frontage" is defined as the space a unit takes up along a line of battle, but in the context of AACW it's used to refer to the limitation on the number of units that can be deployed on the battlefield.
Depending on the terrain and weather conditions, an army is limited in the number of troops that can be engaged. Units that move slowly will also maneuver slowly and so cannot be as readily deployed. Troops that are not engaged are held in reserve and can be sent in to relieve broken units. The game engine handles all of these details invisibly during combat resolution, but it's important to know how the system works so that you can adjust your tactics accordingly.
Combat Units Quota
- For each terrain type, there is a Combat Units Quota and a separate Support Units Quota which limits the number of combat and support elements on each side that can engage in combat during a single combat round (the quota covers all units participating in the combat, not separately computed for each division or stack).
- The quotas are unaffected by weather, except in the case of cities and forts, where for some reason they are somewhat reduced in clear weather.
- Important: for purposes of frontage, artillery is considered a support unit, so it fills up the Support Units Quota.
Assigning to Combat
- Each type of element will use up a set amount of the Combat Units Quota (or Support Units Quota) for each element added to the combat.
- This amount is affected by weather, with harsh weather generally increasing the amount of the quota that an element will use, thereby reducing the number of elements that can engage in combat.
- The quota cost for each type of element is taken from the base unmodified movement cost for the specific type of element in the specific type of terrain. (e.g., cavalry are especially slow in mud, so fewer of them can be deployed).
- The game engine will randomly assign elements to be engaged in combat until the Combat Unit Cost Quota and the Support Unit Cost Quota are both filled. This process is repeated for each combat round.
- The chance of a particular element being engaged is modified by:
- Whether the unit is already engaged (big increase in chance to be engaged again).
- If not already engaged, the number of hits (i.e., health) an element has (e.g., militia have lower total hits than line infantry so are less likely to be engaged).
- If routed, chance to be picked is reduced.
- There is no precedence advantage for different types of elements, and no bonus if you have just one of something (like a sharpshooter), but the element’s special ability will still apply to its unit even if not engaged (first fire for sharpshooter).
- If supply wagons are present, the game engine will not assign more than one supply element to combat as long as there are other types of support elements (e.g., artillery) available to fill the Support Units Quota.
A few specific terrain/weather combinations subtract -25% from the quotas for units in offensive posture only (so the attacker can employ fewer elements than the defender):
- Wilderness/Hills/Mtn/Swamp/Marsh in Mud or Blizzard weather.
- Fort and City in all weather.
In open terrain only (clear/prairie/desert/wood), the Units Quotas are modified by leader (rank)*(offensive/defensive rating) depending whether in offensive or defensive posture:
- Combat Units Quota: (+25 points)*(rank)*(off/def rating)
- Support Units Quota: (+10 points)*(rank)*(off/def rating)
This bonus can be HUGE. A mediocre 1* general with 1 off/def would get a +25 bonus, while a 2* general with a 3 off/def would get a +150 bonus (+60 for support units), so he could bring about 60% more infantry elements to the fight, and twice as much artillery! Other Notes
- Elements from the same unit will all fire against the same enemy unit. If they have overwhelming firepower and destroy the enemy unit outright, the excess firepower for the round is “wasted” and not redirected at another enemy unit.
- With multiple divisions engaged, you may only see casualties in one because the enemy’s fire was all directed at the same unit.
- Corps support artillery (unassigned to divisions) will fire on the healthiest (i.e., strongest) enemy unit. This may not be the same unit that it is directly opposed against.
Still unclear on how elements are assigned if there are multiple units in the stack (separate divisions or brigades). Pocus has not given any indication that units are engaged together, except in his comment about units firing on the same target. It may simply be that if you bring three divisions to a fight and there’s limited frontage, all three might be partially engaged.
Also, on the leader bonus, I’m assuming it must be the stack leader, not the unit leader, because there can only be one unit quota for a battle, so the modifier can only come from one leader. But what about battles with multiple stacks? Does the leader bonus come from the first stack to engage? From the best leader? From the highest ranking?Notes on Terrain/Weather/Unit Type Combinations
There are literally hundreds of different combinations of terrain/weather/unit type. Here are some general comments:
- Cavalry have a big frontage advantage over infantry in clear/city/fort terrain + clear weather, but not in any other conditions, and they especially don’t like mud.
- Forts and cities have the lowest quotas (Forts are somewhat better) and they also impose a -25% quota penalty on the attacker.
- Light infantry have the lowest all around frontage cost, especially in rough terrain and harsh weather.
My frontage analysis data are in the attached Excel file, but all of the data came from the AACW_DB_Terrains file which is linked to in this modding thread: http://www.ageod-forum.com/showthread.php?t=5358EDIT: I've hidden some unit movement types that I thought were not used, but was wrong about MedFoot. To see that, you'll need to unhide the rows.
The unit types displayed in the data file are:
Each of these unit types has a different movement cost for moving into each terrain type, modified by the weather. In AACW, the unit type for movement purposes is shown in the element details window under Movement (not the same as the unit type listed in the upper portion of the window, or the unit type after that in parentheses – yes, it’s confusing that a single element can have three different unit types!). The unit types listed above, that are used in the database, don’t exactly match what you see in the element details window. EDIT: for the most part, infantry in AACW are all HvyFoot. Partisans are LitFoot, but light infantry, volunteers, skirmishers, and militia are all MedFoot. Almost all cavalry is MedHorse (rangers and raiders are LitHorse).Strategy Notes - General
Strategy Notes - Artillery
- Don’t underestimate the importance of the leader bonus for frontage. If you have a stack with a very strong leader, try to engage the enemy in open terrain, and feel free to pack in extra artillery, because the frontage bonus means you can put more of them onto the battlefield in open terrain. On the flip side, if you have a weak leader, stick to rough terrain if possible to minimize your opponent’s leadership advantage.
- Cavalry have 2:1 frontage advantage over infantry in clear terrain, but it doesn't seem very useful -- cavalry actions are usually small, and the frontage quota in clear terrain is so high that you could never fill it with cavalry unless you find a way to make 5 full cavalry divisions and stack them together.
- For cavalry raider divisions, keep in mind that horse artillery are support units, so they don’t detract from the number of cavalry elements you can field. So even in rough terrain, some horse artillery will add a lot to your firepower. Horse artillery…don’t leave home without it.
- In general, a smaller force should always try defend to against a larger force in rough terrain, and a larger force should use caution advancing through the mountains.
- Remember that the frontage limitations are only per round. Battles occur in multiple rounds, and in each round different units can cycle in and out. So, even if your force is too large for the allowed unit quota, it’s still an advantage to have a larger force because your fresh units can relieve your damaged ones. Ultimately a much weaker force will succumb. Yes, the vastly outnumbered Greeks held off the Persians at Thermopylae…but only for awhile.
- Because Artillery fills up the Support Units Quota, they won’t compete with infantry for engagement slots. But, they will compete with other support units. This shouldn’t be a big deal, since supply wagons will only put in one element, but if you also have engineers, signal, and recon units, it could all add up to a reduced number of artillery elements on the field.
- The maximum number of artillery elements in combat is 15 in open terrain (or city/fort) and clear weather. But in any other kind of weather or terrain, artillery is severely reduced (from just 2 elements in mtn/blizzard to 10 in wood/clear, but averaging about 6 across all terrain/weather combinations). This number can be reduced by supply or other support units taking up Support Units Quota points, or increased by the leader bonus.
- Most importantly, leader ability can drastically increase the number of artillery units you can use in open terrain (clear/prairie/desert/wood). An average leader will raise the maximum in open terrain and clear weather to 17. A strong 2* leader can raise it to 30, and a super leader to 45 or more. Basically, a good leader can double your artillery frontage, and a great one can triple it (but only in open terrain).
- Frontage rules put a practical limit on how many artillery elements to put into a stack (or division). But how many is ideal? It depends on the size of the stack – whether it’s a solo division or smaller independent force, or a large multi-division stack like a big corps. With any more than 6 artillery in a stack, you are likely to have some idle artillery units that will not engage. On the other hand, in a big stack, if you have 15 artillery you know you are always bringing maximum firepower to bear.
- My recommendations: 4 artillery per division in a large corps (less if you assign artillery at the corps level). Up to 6 or 7 in an independent division. More in a static defensive position in open terrain, fort, or city. If you have a strong stack commander, increase the amount of artillery and try to stick to clear terrain, but don’t overdo it – in anything but clear terrain your excess artillery is dead weight. Having too much artillery is not a bad thing, except for the cost of producing it and the CP cost of having it in your stack.
- Consider using massed artillery in an Army HQ stack, along with an extra general with the artillerist ability (like Huger for the CSA). Imagine Lee with a super army HQ stack packed with 20+ artillery, in clear terrain, marching to the sound of the guns to support Jackson’s corps. All 20 of those guns will target the largest enemy unit, possibly obliterating it in a singe round! Just don’t let the artillery army HQ stack get caught on its own – better to keep it in the same region as a subordinate corps for protection, since the larger corps stack would be targeted by the enemy in combat. This strategy sounds viable in the game, and it also seems historically appropriate.
- Forts and cities have the same high frontage allowance as clear terrain, but no leader bonus. As it is, the frontage allowance is more than enough to allow you to pack large quantities of artillery into your forts and cities. I wonder how many ships would get by Island 10 with a dozen or more 20# Parrott batteries?
I’m not going to post all of the tables in this thread, because I’m providing the spreadsheet for download (see bottom of post). But to facilitate discussion, I’ll post the basic table on clear terrain and my analysis tables on support units (i.e., artillery).
Please feel agree to disagree with any of my strategy notes, or add more – I’m better at crunching the numbers than seeing all of the implications.
Pocus quote from a BoA thread
(the details will differ but the same principles should apply to AACW): http://www.ageod-forum.com/showthread.php?t=1024
“Before starting an hour of battle, the BE will pick a subset of your unit to actually fight. Why a subset? Because you can’t really expect to have 70,000 men actually fighting on a beach if you land or assaulting a fort at the same time or even firing all at once in a dense forest. This is where the Terrain Contingencies kick in!
Nine regiments of regulars can fight at the same time in clear terrain. Add to that a bonus for each point the Commander of the army has (either in offensive or in defensive, depending on the posture chosen) and another bonus based on the rank he has (so a 3 stars leader can always field a good amount of regiments in plains, even if he won't use clever tactics!). The 2 leader bonuses only apply on clear terrain.
The other terrain are simpler to deal with: there is only a TC amount to consider. Take wilderness for example: 3 regiments of regulars will fight at a given time there (the elements will be rotated after each hour of battle, so you can wear off the enemy), but 10+ Indians tribes/rangers/partisans can be engaged (that's theoretical, you will have a problem finding this number of units in your OOB, but it's to show that you can inflict very serious losses against an enemy in superior numbers, depending of the terrain).
If a unit is appropriate for to a terrain, only a few terrain contingency points will be used, so you can pile on more of them, or have some more room for costlier units (e.g. 3 Indians tribes + 2 militias).
Just use common sense, and it will work: dense terrain are not fit for regular units, but are the realms of lighter ones. A fort can't be assaulted by too many men at a given time, etc.”
Pocus posts in Napoleon’s Campaigns forum: http://www.ageod-forum.com/showthread.php?t=6617
“Some global variables have also been much reduced, for example in AACW you get a +25 bonus per strat rating to frontage if in clear terrain. In NCP this is just only 5 (by request of the Historical Team).”
“Each element has a cost to be deployed on a terrain, given a certain weather (this cost IS his travel time in day by the way).
On the other side, you have an overall quota in lines or supports.
So when the battle happens, the engine will pick one element, pay the cost in frontage, and add it to the battleground. Rinse and repeat until no element can be added.”
“If not already engaged, the more hits it have, the bigger the chance to get committed. If already engaged, the probability to be taken again the next round is much higher. If routed, the probability is lower.”
Pocus on how movement cost is used for a unit type’s frontage cost: http://www.ageod-forum.com/showthread.php?t=11074
“Good question, I had to check the code. This is the 'base day cost' used, drawn from the terrain matrix, and it does not take into account the road network, or the added cost for being under commanded etc.”
“No, MR is not taken into account here. Frontage cost is deduced from the base days needed to travel into a region, because, for a given unit, 95% of the time you see a very strong correlation between how it is easy for her to move into a region and how easy it is to use or deploy the said unit. For example irregulars in wood, artillery in swamps, etc.”