Pros Higher hit probabilities Maybe you already know that for any given single hit, the "hit damage" done by FA (Field Artillery) is the same as is done by a Line of Battle unit. So, an Infantry regiment does exactly the same damage as a 20 lb Parrot, hit for hit. The reason that Artillery
seems to do more damage is because it hits more often. Offensive Fire for USA 10 lb Parrot is 19; for USA Infantry, 10. Defensive fire for the USA 10 lb is 22; for the USA Infantry, 16.
Greater range The maximum range of engagement by Line of Battle units is 4. On the other hand, all artillery elements have a range of 5 or greater. However, the maximum possible range of engagement in the
vast majority of engagements is going to be four. The exceptions are clear/prarie/desert terrain, and woods... and even then, only in fair weather. The implication is that Infantry will immediately return fire in most engagements.
Higher cohesion damage One of the big differences between Artillery and Line units is the amount of cohension damage done. Four or five hits by artillery are enough to reduce any unit's cohesion to virtually nothing, and such units are almost assured of routing. For example, a typical Line Infantry unit inflicts 11 cohesion damage with a hit; but a 10 lb Parrot does 18.
Lower VP when destroyed Athena just
loves to see units destroyed! So much so, that she rewards you with VPs whenever a unit is annihilated. For each Line Infantry unit which you destroy, you receive 4 VPs. But with Artillery units, you only receive 1. Columbiad or 6 lbr, its all the same: you only receive 1 VP for its destruction or capture.
Cons Lower hit capacity A Line Infantry unit has a hit capacity of 20. Most FA has a hit capacity of 12. The "standard" division of 11 Inf + 1 SS + 1 Cav + 4 Arty has a hit capacity of 298. A division with 1 SS + 1 Cav + 15 Arty has a hit capacity of 210. Since most hits inflict 2 damage, that means that the standard division can theoretically absorb 44 more strikes. (Of course, units will route long before this threshold is reached. See the next topic.)
Lower TQ The TQ (or "troop quality") of an element reflects its discipline. From the AACW Manual, pg. 48:
Every hour each sub-unit must check its discipline unless it's intact. If the test fails, the unit becomes shaken and has its rate of fire decreased for the current round. The TQ of Line Infantry units is generally 8 or 9. For field artillery, the TQ is 7. In other words, there is a 30% chance that an artillery unit which has taken damage is going to be "shaken", each round. For Infantry, that chance is only 20%, and in many cases, only 10%. Since the ROF for most Artillery and Line units is two, firepower is cut in half, when shaken. Three notable exceptions are Union Heavy Cav (ROF 3), Sharpshooters (ROF 3), and Siege Artillery (ROF 1).
Lower Evasion values Maybe you already know that "evasion" is
the factor used in determining whether you can move into an enemy ZOC. From the manual:
You cannot enter a land region if the enemy’s Patrol Value divided by your Evasion Value is greater than your Military Control of the region. The "Artillery Division" which has 1 SS + 1 Cav + 15 Arty is going to have an evasion value of 7 + 12 + (15*1), or 34, and a patrol value of 3 + 9 + (15*0)... or 12. The "Standard Division" which has 1 SS + 1 Cav + 4 Arty + 11 Infantry is going to have an evasion value of 52, and a patrol value of 3 + 9 + (4*0) + (11*3)... or 45.
Of course, at the divisional level, this tends to be inconsequential. But once you start considering Corp level operations, the differences start to mount up. You can do the math if you want to, or you can take my word for it: the "Artillery Division" is not going to be very good at preventing incursions, and its likelihood of being blocked is greater than a "standard division"...
especially so after the SS and Cav are decimated in the first engagement.
No police value Artillery units are support units. Consequently,
Artillery cannot take or hold ground. In other words, Artillery has no effect on loyalty or military control. The "Artillery Division" of 1 SS + 1 Cav + 15 Arty has a police value of four. On the other hand, the "Standard Division" of 1 SS + 1 Cav + 4 Arty + 11 Infantry is going to have a police value of 15. Looking further, if we use Pocus's recommendation of 4 Cav per division, then the "Pocus Division" of 1 SS + 4 Cav + 4(?) Arty + 8 Infantry is going to have a police value of 18.
[
Edit 28Sep11: I misunderstood Pocus, when I said that he recommended that a Division have 4 Cav. Instead, a
stack must have 4 Cav
if it has more than 15 elements. If it doesn't, there are penalties to the stack's Hide Bonus, and other penalties as well.
Dixicrat]
High Maintenance The rate of ammo usage in battle for all Artillery (except Gatling guns) is 4, as opposed to 2 for Line units. Thus, the Artillery Division will require 63 ammo per battle; the Standard Division will require 41; and the Pocus Division will require 41, also. I'll leave it to you to calculate the difference in replacement costs. (I'll get you started with a gentle hint: it's rather significant.
)
[
Edit 28Sep11: I want to make it clear that I am not and
never have suggested that players attempt to create an actual Artillery Division. My references to a hypothetical Artillery Division are for
comparative purposes only!]
Even so, early experiments with Artillery Divisions led to surprising failures. 
as an extreme to be compared to the "Standard" Division of 1 SS + 1 Cav + 4 Arty + 11 Infantry.
