GURPS Mass Combat Notes: Mass Combat in Roll20

These are my notes in correction of the mass combat I ran recently. I hope to update this when new data becomes available. This system shows my bias as a scout and analyst lolz.

*Edited: Defense strategies should be double your casualities, not enemies. Thanks to +Il Pella 

Map Preparation

25x25 hex map

40x40 hex map 

60x60 hex map 16km accross

• Units in 25x25 to 60x60 Hex map will encounter each other within the day (following the natural paths found in the terrain). In larger scales the GM and players play it out more abstractly using a larger map assuming the rate of movements found in MC27.
• MC27 is pretty generous for me. My assumptions come from The Small Wars Manual and the very overlooked activity of "Making a secure Camp" and organizing patrols and security. This means half the Foot and Mounted rates because of the camping and cycling of patrols plus reporting. You cannot be too generous with these stats because in the end of the day you move as fast as your weakest unit and generals and historians are always exaggerating about their circumstance and success. Of course it depends what sources and material you adhere to. 
• 0.125 miles or 0.2 km per hex. Units travel their Move score in 15 minutes. They can double their speed, doing a paced run. this is a 2.1 acre or 0.866 hectar hex.  
• Scouts (light Infantry) Move-5 (no enc.)
• Assault Troops (Med. Infantry) Move-4 (light enc.)
• Heavy Infantry (Hvy Infantry) Move-3 (Med enc.)
• Cavalry Move-7
• in stealth, units are better moving in small squads. As such, one hex can hold 200 people or 20 elements. 
• On a 60x60 map it was about 84 hexes for 17km across 10 miles across.
• Forests and Hills block line of sight (see below). 
• Page Settings > Fog of War - Disabled
• Page Settings > Dynamic Lighting - Enabled
• Page Settings > Activate Enforced Line of Sight
• Page Settings > Only Update on Drop
• Natural Paths - You will notice I drew orange lines to illustrate natural paths. This means moving on these paths have the least penalty in footing but this can also mean that enemies plan their ambushes around these paths! The GM can draw trails in advance or draw them on the fly (following the terrain contours). He can put it in the GM layer to be moved into the Map Layer to be visible. I draw on the fly because its easier and only when the player is intentionally Recon. 
• Terrain Score. Terrain and Surprised table in MC29. Put it in Map layer so that you don't have to remember or just remember the score for Woods, Hills, Plains
• Defense bonus. GM just rolls 1d3 Defense Bonus based on the terrain advantage or just simply assign 1 for some terrain, 2 for light woods or rolling terrain, and 3 for hills and dense woods. Note that the unit that gets to "dig-in" and is prepared gets to use the terrain for a bonus. 
• GM layer notes. Event Location Notes can be placed in the GM Layer. Personally I have not much time for this, except for the most critical elements. 
• Tip. Its easy to make a map once you have at least one other map down. Cutting and pasting the trees and terrain is easy, then just re-arrange for the game. 

Unit Preparation

1. Green is Troop Strength. Its easier if I just keep track of one stat with so many elements. 
1. select the status in the Token, choose green, mouse over green and type the TS value to make it immediately visible. 
2. You will need to clump units under NPC leaders or PCs.  Each PC has all its units under command in one token (their token). Adjust the TS and abilities based on the PC's commanding force. Once this is set it will take a lot of time to reorganize such groups (in RL its a big hassle)
1. Typically its broken down to Faster or More Mobile Force, Heavy force or Secondary Mobile force, and Reserve or Heavy force. So 3 groups to one side plus the PCs. 
2. At most 200 or 20 elements in one token. Since this can be time consuming work with your time budget, where less units is less work. 
3. You can break down units one token per element, but you will have to make a Character sheet and save the tokens' values (updating the token)
4. You may stack your Rec Elements up to 5 WT (or 4WT) groups.  
3. PC Units - Unit Settings > Advanced > 4km (2.5 miles), starts to dim at 0.2km (0.13mi), 360; has light 360. 
1. Cavalry have 4.5km (2.8mi), starts to dim 0.6km (0.13mi)
2. NPC units generate "Light" so Players can have a "Chain" of visibility. 
4. Prepare a "Torch" Token. this unit is used to light up an area that is elevated or units spotted while elevated. Typically one hex of light. 
5. Display TS in blue. Click on Unit, click "status" and chose green (or any color) and mouse over the blue in the status options and type the TS value on to that unit. 
6. Display Loss penalty. On the Commander's token, choose orange (or any color), mouse over the orange color and type the loss penalty up to 9. When it exceeds 9, chose the red color, mouse over red and type up to 9. if it exceeds -18, choose the Black color, mouse over up to 2. the combat ends when a force has taken up to -20 or 100% casualties. 
7. Save units at their default value to Character sheets or have them all in GM layer. Cutting and pasting them all to new maps on the GM layer where you duplicate them as you need them.
8. TIP: bandwidth permitting open a duplicate of the Tab you are working on and exit to rejoin as player. Make sure units have GM control so that you can see dynamic lighting in action. I will yet experiment seeing if I can run two tabs with one at GM layer so that I can move "invisible" units. 

Running GURPS Mass Combat in Roll20

I had to make some tweaks. I have a flow chart I made for my players. 

1. Recon Ops.  Intelligence Analysis MC28-29, these are scouting tasks. Even non-recon units can be used for this but at a -5 to relevant Stealth and Operational Security checks. Since these units are more bulky and easier to spot, they need to take precautions that make it harder for them to gather useful intel. 
1. Navigation allows them to spot natural paths, and even find hard to find paths that might give them a way around an obstacle or land feature. 
1. You will notice I drew orange lines towards natural paths. This means moving on these paths have the least penalty in footing BUT this can also mean that enemies plan their ambushes around these paths! 
2. The GM can draw trails in advance or draw them on the fly (following the terrain contours). he can put it in the GM 
2. Survival for hazards and can be used to default for Navigation at -3.
3. Observation allow you to notice and catch things, but the skill to interpret them usefully will be found in skills like Naturalist, Tracking, and various expertise. 
4. Anyone can spot obvious tracks, digging intel from them takes Tracking. 
5. Naturalist Skill is helpful in looking for human passage or use or disruption in the environment.  
6. Torches. Use torches or light sources to illuminate features the PCs spot.
7. Horizon formula is useful if the GM decides how far what PCs sees if they decide to climb. in 15min turns, its hard to climb far enough to break the treeline. -5 climb penalty for scouts, and greater penalties for heavier units.
8. The generous movement rating in Mass Combat can be attributed as having "No Security" (MC29) as a default and moving without security is running.  
2. Maneuvers. 
1. Movement: Units can cover a distance of their movement in hexes in 15 mins. Paced Running doubles movement and costs 1FP per turn and FP+1 for every level of enc. Units with 12+ running would have a discount of 1FP.  more elite units have more FP. 
1. This means Light Infantry can move 5 hexes, run the most, 6 turns of paced running (10 hexes).   
2. Medium Infantry and Bowmen can move 4 hexes, and run 3 turns of paced running (8 hexes). 
3. Heavy Infantry can move 3 hexes, and run 1 turn of paced running (6 hexes).
4. Cavalry can move 7 hexes, and run 1 turn of paced running (14 hexes). 
5. Moving Stealthily. half movement (no running). Commander applies a penalty -1 to -3 to his own Recon and his opponent. 
6. Fatigued Units, FP< 2/3FP total fight at -2 and cannot run. 
2. Concentrate. Perform a Long Action.
3. Ready or Hide. A unit can get ready or stay put and hide, for +4 to Recon checks vs being detected. 
4. Move to Engage. Because tactical maps allow you to pick and chose your battles with more nuance than the default system you will need to be able to move and engage. Move half your normal move to engage, choosing a strategy but you suffer a -2. 
3. Recon Contests. The GM keeps enemy units "Invisible on default" and asks the commanders to roll every turn. When Elements or PCs makes "Contact" roll Reconnaissance Contest (MC28-29). This is a Information Analysis skill (a rare skill in low tech; typically default from Strategy-6 or Soldier-6) contest using modifiers with the Units Present in the "Contact". 
1. Note Recon Superiority (MC32) which is needed for this roll. 
2. Note terrain and surprise table (MC29). the more visible the terrain the harder to achieve surprise (and the higher the Terrain score; imagine the terrain score as a Task Difficulty Modifier the bigger the value, the harder). ex. Plains 8 vs Woods 5 (or 4 in dense woods). 
3. Stacking Units MODIFIERS! The problem with recon is the density of Units within the 2.1 acre or 0.86 hectar area. the more troops in an area the more visible the Army or its elements. A "terrains" carrying WT capacity is equal to 10 - Terrain Rating. Ex. Woodland can hold WT5 or 5 elements while Plains can only hold WT2 until it becomes visible. Every additional WT is a Penalty to the Commander. 
1. So in Plains, units are spread out to hide their numbers. In Forests they are stacked up. 
2. The better the Quality of Troops, they have more TS to WT ratio. 
4. Distance in Hexes. Use the Distances in hexes to determine range penalties. So 3 hexes away is -1 to "spot", 20 hexes (4km) away is -6 to "spot" . 
5. Traps. In the Recon Contest these traps and tricks all play out. It is either you ambush the unit, or you are the one being ambushed.  
4. Type of Battle
1. Encounter Battle (MC34). represents Initial Clashes (no deliberate strategies). Mobile forces can only Attack, Raid and Skirmish, or Mobile Defense.  
2. Encounter Battle, Ambush (MC30). One side is confused (can only rally or full retreat), the other side (typically mobile) cannot use any deliberate, defense (except mobile defense), and retreat strategies.   
3. Pitch Battle (MC34). A head on confrontation with the numbers of forces visible to each side. Any strategy can be chosen.  
5. Individual battles, instead of One Commander. Use the tactical map to inform the circumstance of the PC and his unit. The PC declares his Strategy (or Tactics if he is less than 6 elements), Risk and Significant Actions.  
1. Risk is Built Into Significant Actions.
1. Add the risk modifier in any Strategy.
2. Honor or Dishonor in taking Risky or Unrisky Commander positions depends on the culture and setting. Earlier eras saw commanding from the rear as weakness, while some came to accept it (Sun Tzu and Byzantine Treatises), when it comes to risk PCs should look at their disadvantages first. 
3. Note that the smaller the force, the more risky the Commander tends to be. 
2. GM quickly resolves Risk and Significant Action as a Quick melee if Applicable:  This lasts 3 sec plus Risk modifier. Do not roll for misfortunes of war when the Commander chose risk greater than -3. Use the TS comparison as how many enemies the Commander will face minimum one, -1 for every level of risk below +3. If he is facing 7:1 odds he faces 7 minus his risk below +3. So if he chose -2 risk which is he faces only 2. 
1. The Encounter Ends after the number of seconds - Alive or dead the PC may be. 
2. When the Commanders TS greater and he chose a positive Risk modifier, he will face the most formidable NPC in the unit. 
3. Risk Benchmarks. If your player have a difficulty imagining what risk is, these are some benchmarks.  Risk Modifies the Commander's mortality vs effectiveness in command.
1. (+3) PC leads an Action from the front. Leading by example and showing courage and conviction. 
2. (+2) PC Joins an Action. 
3. (+1) PC Participate in an Action. 
4. (0) PC maneuvers his entourage or guard to block. 
5. (-1) PC is about 3-4 Ranks behind his troops or 10yrds away barking orders.  
6. (-2) PC is about 5-6 Ranks, his orders echoed by lieutenants because he cannot be so easily heard. 
7. (-3) PC lets his lieutenant execute while observing in safety, moving only to bark commands when his lieutenant lapses. 
4. Roll Strategy, against Opposing force. The Player Types out his Total Troop Strength, some notes, and Rolls. The GM rolls and resolves it quickly, he can keep note of the Losses using Orange, Red and Black color markers on the Token with an assigned value (mouse over the color while in Status selection, then type a value). 
1. Position Bonus. Other than tracking Losses, PCs track Position Bonus. The GM just plops a colored Txt Value on the battle field - green for friendly, red for enemy.
6. Step 5 tends to repeat itself until the battle is resolved with -20 or 100% causalities. 
7. After the battle take count of losses and reorganize to how many elements are lost. a 20 element army after -6 or 30% losses will be down to 14 elements. 
8. Maneuvers and Strategies Expanded
1. Retreating allows the Unit to "re-emerge" a number of Hexes equal to their remaining FP. They may not be visible. 
9. 
   

Typical Practice

It all begins with Scouts. The use of scouts aka recon capable units varied in history and the sophistication varied. Maurice and Sun Tzu (and his disciples) had very sophisticated practices documented in the related books The Strategikon and the Art of war. 

The simplest way to go about it is you divide your force in 3s: One in reserve or rear guard, One more mobile, and one more Powerful. The mobile force does Recon coordinating within line of sight with flag bearers, and through runners. 

When forces are too far to communicate with each other in this way, they work on their orders and their leaders personality - typically the GM has to process the Information Asymmetry and it is in Player to RP their PCs in such situations. Familiarity, gestures, and back up measures are important in low tech warfare. 

Working on the Initial Intel, like "Enemy is over There", Recon units use Navigation, Survival, Observation to see how that unit got there via natural paths. Its up to the Commander if he is a good enough pathfinder or Tracker to find a path to intercept or predict the movements of the enemy. 

Good habits and best practices are observed until Contact, which is when Organization (aka Tactics) bring forces to bare. 

Some useful PNG files for your terrain. 

Bad terrain happens a lot. Put this in the GM layer or in the map layer. A skilled tactician, survivalist or naturalist or navigator will be able to read the signs to know that fighting here is bad footing. What you can also do is that fighting outside natural paths is bad footing. 

bad terrain

trail

Elevated Terrain. You cannot go changing the Distance view of the Tokens every time they are on elevated terrain. Simply use the Torch to highlight the areas they would see. 

I came up with this system specifically for my Crusades game and for my Waring States game. I don't know how magic will figure into this because if it exists it will change the fundamentals by such a degree the GM may have to rewrite practices.

Check out Pyramid 3/44 for another Mass Combat Tactical System.