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A battle is an event where enemy military forces meet, and attempt to destroy each other. Although in English "battle" also connotes the stuff that happens in a battle, in the EU2 wiki we use "combat" for that, leaving "battle" to mean the whole fight from start to finish.

This page is a "rules" page, which simply lists the rules that pertain to battles. For tactical help on winning battles, see the article How to Win Battles.

Opening of a Battle

A battle will usually begin when enemy forces are in the same province or sea zone, with a few exceptions:

Also, fleets often "miss" each other at sea; it's easy especially for small fleets to move right through a sea zone without battle.

Effects of Battle

When military units are engaged in battle, they are mostly out of your control. You cannot perform the following actions:

  • giving movement orders, except for retreating
  • splitting, merging, recombining, disbanding
  • boarding fleets
  • using the normal UI for disembarking passengers. However, passengers can still disembark if they are selected via the pageup/pagedown keys.

Sieges are not broken by battle, but if a siege advancement day happens, it is simply skipped for that month with no effect. Blockades are inoperative when fleets are battling; thus it can sometimes be helpful to break an enemy blockade only for one day (the siege advancement day), then retreat, usually back into port.

New forces entering the province or sea zone when there is battle ongoing automatically get added to their side, assuming they are in any war coalition which is involved on either side. There is no possibility for fleets to "sneak past" a battle, once it is happening.


Once a battle has begun, the combat system is used to resolve what happens. Generally, there are sequences of fire and then shock in the combat, with each side inflicting loss of men and morale on the other. This happens repeatedly, until the battle ends (see below).

End of a Battle

A battle typically ends with one of these three outcomes:

  • the human player retreats voluntarily. (AIs cannot voluntarily retreat.)
  • one side loses all morale and is forced into retreat.
  • one side is killed to the last man.

Other ways that a battle can end are as follows:

  • a force is eliminated by attrition
  • peace is declared while the fighting is ongoing
  • one force is annexed by a third country

When a battle ends, warscore is immediately credited to each country on the winning side, and debited from the losers. Warscore values for battles range from +1 for even the tiniest battle up to +3 for a really big battle. (If you know the way in which high-value battles are determined, please add it here.)