Custom Rules:
Mass Combat
By: Arjan Wardekker
Game: Dungeons & Dragons (D&D)

These are rules for running large battles, with groups of about 50 or more soldiers, using Dungeons & Dragons Third Edition. Rules are not designed for spellcasters, so these would have to be played separate from the "normal" soldiers. First, an army's damage potential is calculated, then the tactical result is determined.

Army AC = average armor class = sum of AC's of all your men / number of men
Army Att = average attack roll = 10.5 + sum of men's attack bonusses / number of men
Hits = half the number of men + number of men / 20 * (Army Att - Enemy Army AC)
Soldier Average Damage = sum of average damage for soldiers / number of men
Army Dmg Potential = Hits * Soldier Average Damage
Army HP = sum of all hitpoints of the soldiers
Army Tactical Potential (in percentage) = 100 * Army Dmg Potential / Enemy Army HP

Optional and/or normal modifiers to soldiers' attack bonusses:
- Normal terrain modifiers (see D&D players handbook)
- Magical modifiers (bless, doom and other spells, items, etc)
- Morale modifiers:
An army gets a penalty of -1 to attacks and saves for each 10% of the army that is taken casualty (dead or disabled/captured). If an army's leader is killed or disabled/captured, the army also gets a morale penalty, the size of which depends on the situation (are there capable subcommanders, is the leader a good leader, is there a strong bond between army and leader, etc?) and is determined by the DM. For a normal leader it would be about -2 to -4. Note that killing a leader could (depending on the situation) also grant a bonus to the opposing army. One can also assign a penalty if (a) very capable or important subcommander(s) are taken casualty. The penalty is also at DM's descretion and should be about -1 to -2.
- Flanking:
Bonus to attack for the larger group = (larger group number of men - smaller group number of men) / 100 (percentage) * 2 (twice the percentage will flank; one person flanks together with another) * 2 (flanking gives +2 to attack)
= (larger group number of men - smaller group number of men) / 25

Now check the following table. It refers to one of the Tactical Result Tables (1 to 5) below. The numbers on the side are the Army Tactical Potential for each army (army A and B).

|B A>	0-25%	26-50%	51-75%	76-100%	>100%
0-25%	1	2	3	4	5
26-50%	2	1	2	3	4
51-75%	3	2	1	2	3
76-100%	4	3	2	1	2
>100%	5	4	3	2	1

Tactical Result Tables: go to to the table you where referred to in the table above and roll d20. The Tactical Result is for the army that has the highest Army Tactical Potential (the "winning army", although they might actually reatreat if rolling in table 1 or 2).

Optional modifier to Tactical Result d20 roll:
- Great Leadership modifier (a bonus for the most compentent leader) = winning army's Leader Competence - losing army's Leader Competence
Leader Competence = (leader's level + leader's intelligence modifier + leader's wisdom modifier + leader's charisma modifier)
- Morale modifier: The difference between the morale modifiers of both armies (discussed above). A -1 for each 10% of the army that is taken casualty and a penalty at DM's descretion for killed or disabled/captured commanders and/or subcommanders. Modifier to tactical result roll = winning army's morale modifier - losing army's morale modifier.

Table 1
1 retreat
2-4 slow retreat
5-16 stand
17-19 slow advance
20 advance

Table 2
1 slow retreat
2-4 stand
5-16 slow advance
17-19 advance
20 fast advance

Table 3
1 stand
2-4 slow advance
5-16 advance
17-19 fast advance
20 breakthrough

Table 4
1 slow advance
2-4 advance
5-16 fast advance
17-19 breakthrough
20 total victory

Table 5
1 advance
2-4 fast advance
5-16 breakthrough
17-20 total victory

Slow advance for you means slow retreat for the enemy.
Now check the following table to see what the result means: the Army Dmg that is really done to both armies (taking into account that overwhelming power results in less casualties on the powerfull side) and the precentage of casualties is not actually dead, but disabled and captured instead (taking into account that most men lost in a medieval battle are captured instead of killed). The advancing side can retrieve half of it's own disabled, "captured" men (they are left helpless on the battlefield and can be picked up by medics or soldiers in/behind the advancing army). These men can then be healed.

		% Dmg incurred (winner/loser)	% captured (w/l)
stand		50 / 50				50 / 50
slow advance	40 / 60				50 / 50
advance		30 / 70				40 / 60
fast advance	20 / 80				40 / 70
breakthrough	10 / 90				30 / 70
total victory	0 / 100				30 / 80

- All fractions are rounded to the nearest number.
- Damage dealt is divided as follows: divide half of it equally among all soldiers and after that use the other half to take down the soldiers with the lowest Armor Class (taking down means: do not divide it, but use the damage to kill the soldiers. For example: there are 10 soldiers with each 5 hp left, the remaining damage is 20, that kills 4 soldiers (instead of doing each of them another 2 damage)).
- Might you get a x.5 dead and y.5 captured, decide in favor of the captured: x dead and y+1 captured (again because most losses are captured instead of killed).

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