Diaz Freeform Mass Combat System

 Adapted for 5e D&D from http://methodsetmadness.blogspot.com/2023/05/old-school-mass-combat-i-basics.html

The freeform mass combat system

The hp of a unit is equal to the sum hp of all men/creatures in the unit.

The damage of a unit is equal to the sum of all individual damage, using the listed average (rounding down & ignoring crits). For a unit of 10 men each doing 6 damage (eg from d8+2)  it would be 60.  Reach 10' weapons wielded by Small or Medium creatures increase damage by 50%, rounded down. So eg a unit of halberdiers each doing 7 (1d10+2) damage instead does 7x1.5=10 damage per man in mass combat. Reach 15' weapons wielded by Large creatures, Reach 20' by Huge, and Reach 25' by Gargantuan, have the same effect.

To hit, simply make one attack roll per unit per round. Each successful attack inflicts that amount of damage (in the example, 60).

A unit that has lost half its hp/personnel is Bloodied and has its damage halved (eg 60>30).

When all hp are lost, the unit is eliminated.  All individuals aren't necessarily dead, but they are out of the combat for all intents and purposes.

Missile units must be able to draw an unobstructed line to their target to be able to attack.

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2) Taking damage

When an unit takes damage, just remove it from the unit's hp (UHP).

Single figures (e.g., a single dragon in the battlefield) lose HP as normal. If they survive, they might test morale, and they start the next round with fewer HP.

Area Effect Damage

If a Unit is fully covered by the area, multiply damage by the number of personnel in the Unit. If unit is Bloodied, multiply damage by half the # personnel in the unit.

For partial coverage, each full 5'x5' area covered gets 1 Small or Medium person, each 10'x10' area one Large, each 15'x15' one Huge, each 20'x20' one Gargantuan.

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3) Saving Throws

Use the same reasoning, rolling once per unit.

Scaling

This system is designed to work with the 1:1 rules, and so typically uses the same base scale of 5' = 1 square (1" on tabletop).  For larger battles a scale of 1"=50' may be used. Units of 20'x20' or larger size use square bases.

Unit Size (Range)       Base Area                 Effect on Damage per Attack

10 (6-14) medium     15'x15' (9 squares)                  x1.0

20 (15-24) medium     20'x20' (16 squares)              x0.6

30 (25-34) medium     25'x25' (25 squares)              x0.5

40 (35-44) medium     30'x30' (36 squares)              x0.5      

50-60 (45-64) medium 35'x35' (49 squares)             x0.4

70-80 (65-84) medium 40'x40' (64 squares)             x0.4

90 (85-94) medium     45'x45' (81 squares)              x0.3

100 (95-104) medium 50'x50' (100 squares)            x0.3

On the tactical battlefield, units of more than 100 medium-size creatures should be divided up into multiple units, each of 100 or fewer individuals.  Eg a Cohort of 400 men makes up 4 units each of 100 men. A Battalion of 800 men makes up 8 units each of 100 men.

Unit Size (Range)       Base Area              Effect on Damage per Attack

10 (6-14) large     30'x30' (36 squares)                  x1.0

20 (15-24) large   40'x40' (64 squares)                  x0.6

30 (25-34) large   50'x50' (100 squares)                x0.5

On the tactical battlefield, units of more than 30 large-size creatures should be divided up into multiple units, each of 30 or fewer individuals. Eg a cavalry company of 120 cavalry makes up 4 squadrons each of 30 cavalry.

Unit Size (Range)       Base Area                  Effect on Damage per Attack

5 (3-7) huge                 30'x30' (36 squares)        x1.0

10 (8-12) huge             50'x50'  (100 squares)     x0.6

On the tactical battlefield, units of more than 10 huge-size creatures should be divided up into multiple units, each of 10 or fewer individuals. Eg a frost giant platoon of 40 giants makes up 4 squads, each of 10 giants.

Unit Size (Range)       Base Area                   Effect on Damage per Attack

5 (3-7) gargantuan       50'x50' (100 squares)     x1.0

On the tactical battlefield, units of more than 5 gargantuan creatures should be divided up into multiple units, each of 5 or fewer individuals. 

Movement Rate per Round at 1"=50' Scale

20' (Dash 40'): 1" Double Move (no attack)

30' (Dash 60'): 1" Double Move (no attack); with 30' bonus move action, may move 1" & attack

40' (Dash 80'): 1" Move + Attack, 2" Double Move (no attack)

50' (Dash 100'): 1" Move + Attack, 2" Double Move (no attack)

60' (Dash 120'): 1" Move + Attack, 2" Double Move (no attack)

1 vs Many Melee Combat, 10:1 scale

1 can be attacked by 1 reach 1 Squad, or 8 individuals.

1 can be attacked by 2 reach 2 Squads, or 20 individuals.

One (eg PC) vs Many combat. 

1. The PC fights only the front line of the unit. The unit gets 3 individual attacks, 6 with Reach weapons. 

2. The PC is surrounded by the unit. The unit gets 8 individual attacks, or up to 16 with Reach weapons (or 5/10, if bloodied, ie below half hp). This works great using a 3x3 unit base at 10:1 scale, a PC in the middle of the enemy unit has 8 adjacent enemy squares.

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Sample Unit Stats at 10:1 (Squad) Scale

Light Cavalry: Move 60' AC 16 HP 16 Longsword Att +4 Dam 6, Javelin Att +4 dam 5 rng 30'/120'. Squad UHP 160/80 UDam 60/30 or 50/25 Size 6x6

Halberdier: Move 30' AC 15 HP 16 Halberd Attack +4 Damage 7 (10) reach 10'. Squad UHP 160/80 UDam 100/50  Size 3x3

Militia Archer: Move 30' AC 13 HP 11 Shortbow/Hand Axe  Att +3 Dam 4 rng 80'/320' Squad UHP 110/55 UDam 40/20 Size 3x3

Militia Spear: Move 30' AC 15 HP 11 Spear Attack +3 Damage 4 reach 5' Squad UHP 110/55 UDam 40/20 Size 3x3

  

Sample Units at Other Scales

20 goblin archers AC 13 HP 7 > UHP 140/70 Shortbow ATT +4 dam 5 > Udam 60/30.

20 orcs AC 13 HP 15 > UHP 300/150 Great Axe ATT +5 dam 9 > Udam 108/54.

20 light cavalry AC 14 HP 16 > UHP 320/160, Sword ATT +4 dam 6 > Udam 72/36.

100 heavy infantry AC 15 HP 16 > UHP 1600/800 Pike ATT +4 dam 7 > Udam 210/105.