Mass Combat for D&D 5th Edition

Introduction to Mass Combat

If your’re like me you love the  idea of incorporating armies and mass combat into your D&D campaign. In particular, your players want to lead an army into battle against a host of orcs, demons, and other minions. Seeing this demand, Wizards of the Coast released two versions of mass combat for it’s 5th Edition rule set as part of its Unearthed Arcana series.

Unfortunately, I feel that something is missing from both of those iterations. The first is that it treats leading an army like a table top war game rather than an experience in generalship. And two, its challenging to fit the flow of combat into the personal narratives of the characters, such as encounters based on critical moments in the fighting.

Here is an alternative to the mass combat rule set designed to give meaning to you troop choices, provide a narrative backdrop for your characters in the midst of mass combat, and emphasize strategic decision making in the same style as commanders of antiquity. Fair warning, it’s a long read!

This guide is broken out into three sections: On War, The Commander’s Tent, and Unleash Hell.

  • On War provides an overview of the battlefield and the flow of combat.
  • The Commander’s Tent describes the major decisions your characters must make before battle.
  • Unleash Hell covers the phases of battle and key decision points during the fighting.

On War

Deridan slowly sipped a glass of wine. Despite the exquisite vintage, it tasted rancid. It was only his nerves he knew, and not the quality of the grapes. He looked around the command tent, impressively furnished for his use, which made the situation all the more absurd. He wasn’t a leader. Sure, he’d hunted orcs all his life and plundered his share of forgotten ruins, but he’d never asked for this. But ever since he’d saved the Duke’s life the man wouldn’t leave him alone. And now, with another orc uprising on the horizon, he found himself entrusted with command of the whole army. If he failed, the foul beasts would rampage across the countryside and thousands would pay the price.

The Anatomy of an Army

Anatomy of a medieval, fantasy army

Armies are organized into five major divisions known as Troops. These form the major fighting units within your army, and their organization is key to your success on the battlefield.

Three troops comprise the front line of battle: your Center, Left Wing and the Right Wing. Supporting the front line is a single troop known as the Support troop. Behind them you may also maintain a single troop of Reserves. In battle, the centers and wings face each other while support troops have their choice of targets.

Your strategy is how you organize each troop within your army. Do you place more troops in one wing versus another? Do you have any support troops at all, since they require ranged attacks? And perhaps most importantly, do you maintain a reserve in case the fighting goes against you? Your player characters can lead the troop as it’s Officer or join a troop as a member of the unit.

The Flow of Battle

Diagram of the flow of fantasy battles.

All fighting takes place simultaneously as the different troops clash. This process is mostly automatic in that your center will attack the enemy’s center. However, there are also key decision points during the fighting where a troop commander can influence the course of the battle.

  • Support troops attack an enemy troop with ranged weapons and magic.
  • The main battle line clashes – center, left and right.
  • Units can lose morale and rout, fleeing from the battlefield.
  • Reserves may reinforce a break in the main line caused by routing troops.
  • Troops in the main line that are unchallenged may pursue routing troops, envelope the next troop in the main line, or attack the support troops.

Combat ends when all three troops in the main line of battle rout or are destroyed. This may include the reserve troop if they reinforce the main line rather than withdrawing from battle.

Few historical armies had the discipline, training, and communications needed to move and fight as independent units. This limited control to voice, messenger, banners and instruments. Commanders planned the battle beforehand with their officers and advisers. Then they entrusted subordinates with command of each sections of the army, hoping that they followed the battle plan. Of course, some chose to act differently based upon their own experience, instincts, or fear.

The Commander’s Tent

Deridan fought the urge to scratch. Sweat poured down the hollow of his back, but he couldn’t afford weakness in front of his key officers. His childhood companion and adventuring partner winked at him from the back of the tent. He gave a slight nod in reply and then gave his orders. The assembled lord wouldn’t like it. He was ignoring traditional wisdom and putting his strength in the wings. But if there was one thing he knew, it was orcs. They’d come in hard and fast, straight up the center. As long as his line of pike held the initial charge then they could surround the orcs annihilate them.

Building Your Army

You build your army by the ground up, first by determining the type and number of NPCs, PCs and monsters that comprise your army. You then divide those units into their troops. While you do not have to assign units to every troop, doing so can leave you at a disadvantage in battle. Next, you assign a commander to each troop, who can issue special orders with advantages bases upon their attribute modifiers. The commander can be a player character or an NPC controlled by the GM.

The GM and players should work together to create the army. Some methods include growing the army organically as part of your story, assigning a pool of XP to spend on NPCs and monsters, or by assigning a gold value to each CR.

  1. The most natural way to build an army is as part of the campaign or story. As the characters grow in power they may earn a stronghold, followers, or titles of nobility that bring with them many soldiers. It is up to the GM to design an army sufficiently challenging to face the players.
  2. A second option is to assign an XP pool for the players to build an army. Each CR in the Monster Manual has a corresponding XP cost ranging from 25 XP at 1/8 CR to 62,000 at 24 CR. This method of creation favors larger numbers of cheaper units, which while accurate may undervalue the contribution of a more powerful creature. There are optional rules in the third section to help balance higher end creatures facing numerous, weaker opponents.
  3. You can also have the characters spend gold to hire and pays soldiers for the duration of the campaign. Divide the unit’s XP by 100 to determine their cost in gold. This is ideal for campaigns of short duration and mostly represents initial upkeep and signing bonuses. Each soldier also requires 2 silver pieces per day, which is paid in the form of food and supplies. A soldier’s regular pay comes from looting and ransoms and they expect to return home very shortly. If this is a professional army demanding regular pay then daily upkeep increase to 2 gold per day.

Mustering the Troops

The ideal time to organize the army is in the classic tent scene where the commander gathers the army’s leaders. GMs should add to the drama by having NPCs demand special favors. For example, the dwarf berserkers demand the honor of serving at the very front and center. The wizard guild argues that they are too important to waste in the front lines, and should be kept safely as support troops. An uppity noble can demand the honor of commanding the flank over a player. The commander must find a way to balance these many demands.

Once you mustered your units, you must divide them into up to five troops. The three front line troops can utilize both melee and ranged attacks, while the support troop is limited to ranged attacks of greater than 60’. The reserve cannot participate in battle until they enter the front line of battle.

Example of a unit building table for one of 5 troops

This example shows a single troop with three unit types and one commander. Fill out each field using the average numbers in the Monster Manual for hit points and damage. Front line troops can use both melee and ranged attacks while support troops can only use ranged attacks with a distance greater than 60 feet.

Burst damage is only calculated for spells or abilities that can be used three times without a long rest. For example, a wizard or sorcerer will use a standard spell or attack, but they are also capable of unleashing more powerful spells against a larger number of targets. If they can use these spells three times before a long rest then they count as burst attacks.

Use the Target in Areas of Effect table from page 249 of the DMG to determine the number of targets for AOE spells or abilities. Multiple the average damage of the spell or ability by that multiplier in the table. For abilities that grant a Saving Throw, assume that half of the attacks cause full damage while half cause reduced damage. Abilities that recharge during an encounter can be used as a burst attack. The GM has final say on what constitutes burst damage.

Alternatively, you can replace burst damage with healing, so clerics with three healing spells can heal damage to the troops strength rating at the end of that round of combat rather than dealing damage. The GM should use their discretion with spells and abilities to try and reflect the greater strength of certain creatures and classes.

The Troop Attributes

Example of a final troop table

The troop attributes are comprised of an average of all unit stats, rounded to nearest whole number. If you wish a more nuanced approach you can consider rounding to the nearest half number, but the final result when comparing troop attributes in battle must equal a whole number.

  • Unit Mass (# of Units * Size)
  • Strength (# of Units * HP)
  • Defense (# of Units * Individual AC) / # of Units
  • To-Hits (# of Units * Individual Attack Modifier) / # of Units
  • Attacks (# of Units * Individual Attacks) / # of Units
  • Damage (# of Units * Individual Damage) / # of Units
Not every player group is ready to command an entire battle. In this case, they may be given responsibility for a single troop. Add each character as a member of the troop and assign additional units as needed. Of course, only one will have the responsibility command. Perhaps they are forced into the front as cannon fodder. Or, they may be held in reserve to strike at a key moment in the battle

Mass is an optional rule that reflects the size and presence of the troop. Small creatures count as .5, Medium creatures as 1, Large creatures as 4, Huge creatures as 9, and Gargantuan creatures as 16. Troops with a mass larger than their opponent will have an advantage in battle.

In addition, some battles will favor one side. For example, a troop holding a city wall or fortress will have a cover modifier to AC. The GM determines this modifier and denotes it in the Cover field.

Once completed you will have up to five troops forming your army, each with an attribute block based upon the combined fighting abilities of its units. Your commanders will ultimately decide the actions of each troop in battle, so choose?

Reconnaissance

It is up to your GM to decide how much you know about the opposing army. They should reward their players for engaging role play and decisions, such as sending out reconnaissance troops, gathering the information themselves, or using magic. Successfully role playing and rolls should provide some (though not all) of the following benefits:

  • Rough understanding of how the foe likes to organize their army, such favoring a strong center or building a balanced army with ample reserves.
  • Numbers of key enemy units. An orc clan’s numbers may be uncounted, but the fifty ogres they recruited stand out from the rest.
  • Information about key enemy leaders and their preferred approach to battle.

Unleash Hell

The endless night slowly gave way to morning. He wished he’d gotten some sleep before the coming battle, but it was nothing a friendly cleric and some magic couldn’t help him with. His heart pounded in time with the trumpets as his troops mustered and marched onto the field. With pride, he noticed each wing taking position as agreed. It’d taken some convincing, but the nobles were following into line. His pounding heart sounded like an anvil as the invaders gathered before his army. He let out a slight sigh of relief as they also formed up as expected. Everything was going to plan! His sudden surge in confidence took a turn for the worse as six hill giants plodded out from the woods. Each one of them pulled a sack overflowing with large stones.

Phases of Battle

Battle is divided in rounds, which occur simultaneously for each player. Once a round is completed, you start from the beginning until a winner is determined.

Command Phase

  • Determine Attacker: This is predetermined based on the battle or randomly decided.
  • Deploy the Reserves: The reserve troop commander decides if they wish to reinforce one of the three line troops if it routed at the end of the last round.
  • Support Troop: Each support troop commander determines the unit that they will attack in this round. The target can include the enemy support troops or any of the three front-line troops.
  • Flanking: If a front-line troop routs an opposition troop in the last round, the command can choose to pursue the routing troops, envelope the next front-line troop., or attack the enemy support troops. This is blocked by the reserve troops if they deploy.
  • Issue Orders: Each troop commander can choose to issue an order.
  • Compare Mass: If using mass, provide a bonus modifier to the troop that is larger than its opponent. 50% larger gives a +1 To-Hit. 100% gives a +2 To-Hit. 200% or more gives a +3.

Orders

Each commander may choose to take an opposed ability modifier check against the opposing troop’s commander. Each ability provides a separate benefit; however, if you lose then enemy commander receives that benefit. It is possible to lose your opposed check as well as lose to the enemy commanders opposed check, such is the fickle hand of fate.

  • Cut Them Down (Strength): Receive a +1 bonus to your troop’s Damage.
  • Take Aim (Dexterity): Receive a +1 bonus to your troop’s To-Hit.
  • Shield Wall (Constitution): Receive a +1 bonus to your troop’s Defense.
  • Rain Fire (Intelligence): Use your troop’s Blast Damage for this turn. You can use this a maximum of three times, but a failed check also accounts against your three opportunities.
  • Read the Battlefield (Wisdom): You prevent your opponent from receiving any benefits from their Order for this round.
  • Rallying Cry (Charisma): Receive a +1 bonus to your next morale check.

Battle Phase

Table for calculating hits and damage

The battle phase resolves in a strict order. First, the support troops attack a target of their choosing. This is followed by the Center, Left Wing, and then Right Wing. All combat occurs simultaneously, so while you determine damage in sequence, no effects take place until the resolution phase. To determine damage, follow the follow process for each troop.

  1. Add the temporary bonuses to troops attributes for Orders and Mass.
  2. Determine the number of attackers needed to hit by subtracting your unit’s To-Hit value from the enemy troops Defense value. Based on the Mob Attack rolls on page 250 of the DMG, this determines the percentage of attacks that hit.
    1. Deridan’s troop has a To-Hit modifier of 3. Against an enemy with a defense of 15, 45% of his units score a hit.
  3. Multiple the troops total number of attacks by the number of attacks available.
  4. Multiple the average damage value by the number of successful attacks to determine how much damage you cause the enemy troop.

Support

Support troops only deal half damage unless using burst damage. This reflects the difficulty of targeting individuals when in a mutually supporting line of battle, such as behind a shield wall. In return, support troops do not take damage from their targets unless they are also targeted by support troops.

Flanking

When one front-line troop routs its opponent, there are several options available during the next round of battle. First, the reserves may choose to stem the tide and take position on the front-line, either as the center or one of the wings. Otherwise, the unopposed force is now considered flanking and they can take three options: envelope the next troop in the main battle line, pursue the routing troops, or directly attack the support troops.

Envelope allows you to attack a single front-line troop with multiple troops. For example, if your right wing is unopposed, both your center and right can attack the enemies center troop. In this situation, the enveloping force causes X damage while taking X damage in return.

Pursuit allows the flanking troop to attack the routed troops. They forgo attacking the main line or support troops and instead deal double damage to the routed troop without taking any damage in return. This can only be done once per routed troop.

Finally, the flanking troop can directly attack the support troops, dealing normal damage. In this situation, the support troop is prevented from attacking any other troop on the opposing side.

Resolution Phase

This phase occurs immediately after the Battle Phase. Each troop takes the damage from the battle phase and resolves their rout checks.

  1. Subtract damage from the enemy units Strength to determine their Remaining Strength.
  2. Each unit must make a Rout check when their Remaining Strength drops below 75%, 50% and 25% of their maximum Strength.
  3. The battle ends when all three front-line units are routed: Center, Left Wing and Right Wing. Either player can also choose to withdraw at any time. Like routing, your units take damage from the enemy without causing damage on that turn, but the damage is not doubled.

Rout Checks

Route checks are CHA check for the troop commander to steady their soldiers in battle. The DC corresponds to the overall damage suffered by the troop. 75% strength is a DC 10, 50% strength is a DC 15, and 25% strength is a DC 20. If the commander passes all three CHA checks it is assumed that the unit will fight to the bitter end.

The GM can choose to apply an additional modifier to the roll based upon the player’s actions. For example, a particularly talented bard may be worthy of an additional bonus. On the other hand, a negative modifier should apply if they army hasn’t paid the troops in months or the soldiers are treated in a callous, brutal manner. Modifiers should be minor, no more than +/- 1 for each circumstance

Units that route no longer impact the battle. They lose all discipline, discarding their weapons and armor in a desperate attempt to escape the enemy.

Resolving Casualties

When the battle is complete, your victorious army will have taken losses and the defeated army may have troops that survived to fight another day. Each army must subtract the damage to a troops strength from individual units to identify how many soldiers were killed or are too crippled to continue in the war. The units are chosen by the troop commander, and a unit must absorb its entire hit points in damage. This prevents piecemealing damage across your soldiers leaving everyone alive.

  • Deridan’s troop won their fight, but took grievous losses in battle comprising 600 in damage. He determines that he lost a mix of his fighters for 5 Veterans (290 HPs) and 28 Guards (309 HPs).

The GM can allow the players to mitigate some of the deaths if they have particularly powerful healing magics available to them, such as cure critical wounds, heal, or any type of life restoring spell such as Raise Dead. One soldier lives for each unit in the army that can caste one of those spells.

Tips & Strategies

Deridan’s troops barely held against the rampaging orcs and their hill giant allies. For a moment, their line almost broke as a giant champion shattered their shield wall. While not experiences in the art of command, this was something he knew how to face. He gave his closest companions a wink and then let loose with his fiercest battle cry. Sword raised high, he charged the giant in a final confrontation to seal the enemy’s fate and end the fighting.

PC Encounters

As the battle develops it will present opportunities for the player characters to save the day. The GM should encourage the players to take personal action at a critical moment in the battle, perhaps influencing the outcome of the engagement. Since the GM already has a troop list with unique units, they can pull an appropriate, deadly encounter together to challenge the party.

This encounters should come at a critical time to give the characters an opportunity to swing the battle in their favor. This is especially important in battles where all of the characters are in a single troop.

  • A troops routs early from failing a check after only 25% damage. If the characters survive against an overwhelming encounter for enough turns the troop will rally.
  • If there are no reserves to reinforce the battle line then the characters can attempt to delay an envelopment for one round of battle by tying up the attackers.
  • Instead of ending the battle at the moment of victory or defeat, the opposing army’s commander begins a powerful summoning spell. The characters must stop the ritual before the magic is unleashed upon their allies.

Battlefield Strategies

Your success on the battlefield depends largely upon how you organize your troops. Common methods in the past were to make one wing stronger than the other or focus on the center. Your players can even choose to leave a troop empty, such as the reserves. These decisions are often made in the war council, and NPCs will likely challenge an unorthodox tactics. This is a great time for your players to debate the strategy, rally the troops, and then wait out the long night before the coming fight.

GMs should point their characters to great historic battles for inspiration.

  • At Cannae, the Romans strengthened their center while Hannibal emphasized his wings. Hannibal’s wings quickly surrounded the Roman army, achieving a double envelopment. Without reserves and surrounded, the Romans were annihilated.
  • At Leuctra, a Greek army from Thebes defeated the Spartans. Epaminondas put the bulk of his strength in his left wing, which routed the Spartan wing before they could defeat his weaker center. Without a reserve and their army outflanked, the Spartans withdrew and lost the battle.

Of course, these strategies were risky! If the stronger wings had failed to overpower their foes then the enemies center would have won through and crushed them.

Optional Rules

Siege Engines: The support troop may utilize siege engines in battle. Each siege engine unit represents itself and the engineers that load and fire the weapon. They have no ability to deal melee damage if attacked by a flanking troop. For mass combat, their hit points equal the number of crew required to man the weapon multiplied by 9.

Cover: A troop may have the advantage of cover in battle. This represents having the time to prepare defenses in the field or taking position behind strong city walls. For light field defense this results in a +1 modifier to the troops defense. Strong walls and towers grant a +2 modifier. The GM should determine if the attacker has anything that will allow them to avoid such defenses, such as access to secret tunnels.

 

Phew, that’s a lot of rules. Take a look and let me know if you have any comments, thoughts, opinions, etc. I’d love feedback! I if interested, I’ll post an Excel file and examples for building your army.

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