In custom battle mode, players select units for their army and then go directly to a battle.
- Each army is moved together as a group with its Lord.
- On the campaign map, each army must have a Lord at all times. If the Lord is killed/wounded in battle, then a new Lord must be recruited as soon as the battle ends.
- Each race has a different style of flag for their armies on the campaign map.
- Armies can also contain heroes who can join/leave armies as they please.
- Units are recruited to armies/Lords, whereas Lords are recruited from settlements.
- Armies can suffer attrition due to high levels of corruption or an inhospitable climate or rough terrain.
- Units take damage and lose troops (entities) through attrition and battle. Army losses can be replenished through replenishment.
- Units which have lost troops can be combined with each other to create a single stronger unit, however the unit's rank will drop to the lower rank of the two original units.
- Units can also be disbanded altogether or re-named to something else.
- When an army enters a settlement, it is said to garrison the settlement.
- Garrison armies are a special army automatically generated by a settlement to defend itself.
- Garrisons are increased by upgrading the main settlement chain buildings, and by constructing defense buildings (eg: Basic Walls, City Watch).
- Garrisons must be fought and defeated to take a settlement.
- Garrisons are often not led by a lord, though a highly upgraded garrison may have heroes to lead it.
- Garrisons cannot leave the settlement they protect, and so are only useful defensively.
- A garrison will participate in any battle that occurs inside the zone of control of their settlement, even if the battle is not an attack upon the settlement.
- Armies (and also lone heroes) may embark upon the ocean or other waterways. Their unit model will switch to a ship.
- If an army moves between the land and the sea, they may not move further that turn except if they did so through a port settlement.
- Armies who end their turn in High Seas terrain will be subject to attrition.
From Total War: Warhammer II onwards:
- Armies on the ocean may be subject to attrition from storms, maelstroms etc.
- Armies on the ocean can treasure hunt at shipwrecks and other points of interest.
- There are special naval stances.
- Dark Elves Black Arks and Vampire Coast Flagships can be found on the ocean.
Fighting battles on the ocean:
- In Total War: Warhammer, embarked armies can only autoresolve on the Ocean. This means armies which do poorly in autoresolve are very vulnerable.
- As of the Aye-Aye! Patch for Total War: Warhammer II, embarked armies can actually fight battles on the ocean. The battle will be fought on special island/Black Ark maps.
- Orders are given to units in an army, not individual soldiers.
- Each unit in the player’s army is represented by a Unit card. These are shown on the Army panel.
- Up to 8 armies may engage in a battle (4 per side). However only 40 units (2 full armies worth) may be controlled by the player at once.
- If too many units are present in a battle, then some will wait as reinforcements until other units are destroyed first. Reinforcements enter from the map edge.
- In battle your armies have green health bars, allies blue and enemies red.
- In battle, each army is always led by a Lord, who acts as the commander/general.
Deciding on an army composition is a strategic consideration that depends entirely on the kind of war you are currently prosecuting and your enemy. When planning, focus on the following:
- How well protected are enemy units?
- The enemy dictates the kind of force you should field. For example, low tier Greenskins units have little armor and their missile forces have limited range, allowing Dwarfs to field Quarrellers to decimate their units thanks to good damage and superior range. However, when fighting Chaos, their armor means that Quarrelers sharply lose their power at range and should be swapped out for units with armor piercing capabilities, like the organ gun.
- How large are enemy units?
- When choosing army units, consider the size of enemy units. Swarms like Spearmen or Skavenslaves require a different hand than single, powerful units like Chaos Giants. The former are vulnerable to area of effect attacks and well protected units that can deal high damage to multiple targets or break their formation (cavalry charges). The latter will typically shrug these off, but respond well to application of units that deal high damage to single targets. Sniping an orc warboss using a bastiladon can effectively break a larger ork army.
- What kind of faction do they represent?
- Each faction has their strengths and weaknesses. The Vampire Counts lack ranged units, so keeping distance and pummeling them long range can be effective if you hold the line. Dwarfs are slow, making them vulnerable to flanking maneuvers. And so on and so forth.
- What is cost-effective?
- Finally, warriors win battles, but bureaucrats win wars. Do not spend more money than is necessary to counter enemy armies. An expensive army lurking behind enemy lines to weed out low tech rebels is a waste, when one composed of low tech units can achieve the same thing, except cheaper.