When a character leading armies moves into a province occupied by an enemy army, there is a battle. In battles, fleets can be used on land (they disembark their marines for the battle) and armies can fight at sea. Sea battles are basically a series of boarding actions and therefore are somewhat similar to land battles. Battles are fought at the end of the phase, after all characters have taken their actions.
If you attack a neutral province, and another player attacks it in the same phase, or attacks while you are still contesting the province, either player may be first to battle the defenders. Your chances are proportional to how many armies you have.
The two supreme commanders at the battles are the characters with the largest troop contingents, the tiebreaker being the best Tactical ability.
If a character who leads no armies is present in a province where a battle occurs, he will appear at the battle to take over in case the supreme commander dies (but will not have to fight a duel). He will not appear if there is no supreme commander already at the battle for his side.
If the defending armies aren't led by a character, they are led by the "provincial garrison commander", who has no abilities and is present for that battle only.
Before the battle, the two supreme commanders may fight a duel. The armies which were led by the loser of the duel will become demoralized and will be reduced in strength by 25%. More details concerning duels are given in the Special Encounter Plan rules [5.10].
When a battle occurs, the armies of the two forces are lined up against each other. The line may be shortened by mountainous or wooded terrain on the flanks of the defender, so that the defending force only has to defend a small line (see the Terrain Table). The length of the line is limited to the line length of the smallest force. The two opposing forces place their best armies in the front of the line. The weaker armies usually line up behind the front line, and contribute 50% of their strength to the battle. If there are enough armies for a third line, they are only 25% of their normal strength, and so on. If a battle line is shorter than the terrain allows, the flanking second-line units of a force which is superior in numbers may outflank the enemy force. If they do that, they count as 100% strength instead of 50%.
Non-humanoid units (Eagles, Dragons, Whales and Mermen) can attack from above or below and contribute 100% of their strength to the battle. If there is an enemy unit behind the front lines for the non-human unit to attack instead of a unit on the front line, it will attack the rear unit instead (the non-human unit and the rearward unit will both be at 100% strength in this case.) However, if the non-human unit has low strength because its leader has insufficient Druidic ability, it will be held back and will throw its low strength into the attack on the front-line unit.
The reasoning for this rule is that the swooping attacks of air units and the underwater attacks of Whales and Mermen at sea would naturally carry them past the front lines, especially if the enemy is fighting in close-order formation. So a second-line unit should always be at 100% strength if an air unit is overflying or a sea unit is attacking underwater the unit ahead of it in the front line.
All non-humanoid units (air units, whales and mermen) become less effective when more than one is used in a column, or more than one is attacking a single enemy unit. A second non-humanoid unit attacking an enemy unit is at 1/2 strength, a third is at 1/4 strength, etc. Non-humanoid air units, non- humanoid sea units and humanoid units are considered three separate groups when halving strength in this way.
Generals are sometimes able to take account of elephant performance and the "nemesis" effect when lining up their units. The chance of being able to make a switch in any column is (Tactical-Ability / Line-Length). Switches can only be made within the same column, and the defender always gets the last chance to switch. The switch will only be made if the army strength of the current front-line unit is less than the strength of a rearward unit, after adjustments are made for all nemesis effects.
There are several factors that modify or affect the strength of units in battle. These are detailed beneath the Army Type Table. For Druidic Kingdoms, if a monster in a province where a battle is being fought is closer in alignment to Druidic than the player he is fighting, it may come to help the Druidic cause. A very powerful monster in a 1-column battle in mountains may even have a better effect than the fanaticism sometimes given to armies of Good alignment.
There is then a number of contests equal to the length of the battle line. The strengths of the combatants are totaled up and compared. A 4:1 ratio is needed to assure victory, while a 1:1 ratio gives a 50% chance of winning. The side that does best in these contests wins the battle. The computer decides which armies were eliminated in the battle by comparing the strengths of the armies fighting in the contest. Fleets fighting on land provinces would generally be reduced to Depleted status instead of being eliminated.
After the battle, the faster units in the victorious army can pursue and possibly destroy some of the losing armies. In this pursuit, army speed is the most important factor in catching the defenders or evading the pursuers. Retreating units fight with the 25% bonus given to defenders, but suffer a -1 quality penalty due to their demoralized state.
Generally speaking, about 25% of the victorious infantry and 75% of the cavalry will attempt to pursue the retreating armies. Especially fast units such as light cavalry and air wings can attempt more than one pursuit. If a retreating army is unable to fight the pursuing unit to a standstill in a one-on-one battle, it is destroyed.
If the defeated army has little hope of winning a second battle, it will retreat into an adjacent friendly province. If retreat is impossible, Green and Depleted units will be disbanded into the population, while Average and better units may disband into mercenaries, usually marching a few provinces away from their attackers at the end of the turn. You can not hire them that game turn.
If the attacker destroyed all defenders or forced them to retreat, the province becomes part of the attacker's Kingdom and it will pay taxes to its new King each turn. If the attacker was forced to retreat, his armies must retreat into the same province they invaded from, or a province adjacent to the province they invaded from. Retreats are conducted separately for each character who leads a contingent at a battle. This is important if the only retreat route is to the sea, and one leader has all the Fleets. If you kill an enemy general in a duel, the troops will usually carry his body with them in their retreat. That would be the reason why you don't see his grave in the province of his death.
Armies of the winning force that did well in the battle may have their quality increased by 1 level, although most troops will never become Crack and very few will ever become Elite. Some armies in the losing force will probably have their quality level decreased by 1 level, although a defeated force that does not retreat can either improve or decrease in quality. The chance of rising or falling in quality decreases as armies gain in quality.
A unit has less than the normal chance to improve in quality if it is inadequately led. If it fought as a Green or Depleted unit because of insufficient Druidic ability, it has 60% and 20% (respectively) of the normal chance to improve.
Factors in a decision whether to give up the fight for the province, or stay to defend, are as follows:
If an attacker invades a province but fails to destroy the defenders or make them retreat, the province still belongs to the defender, and is called a "contested" province. If the attackers still have at least 1 movement point for each army, they will be used to force another battle in the next phase. If not, both armies will encamp and wait for spring of the next game turn.
If you start a game turn in a contested province and don't move out, your armies will use up a movement point to fight a battle at the end of phase 1. The defending Kingdom can't force a battle in a contested province even if all its armies can move, nor is a battle caused by reinforcements sent to the defenders. If the province is conquered, the attacker uses another movement point.
The leader who invaded the contested province will execute his orders in the next phase, except that it's illegal to move from the contested province to an unfriendly province. You can, however, move from a province owned by a neutral player-King to an unfriendly province.
Let's take the example of an all-infantry army led by a Hero with March skill of 2. It moves into a province (using 1 movement point) and wins the first battle, destroying half of the defending armies in the pursuit. But the defenders decide they still have a chance. They stay, and in the next phase, the attackers use up a movement point to force another battle. They wipe out the defenders, use up another movement point to occupy the province, and are left with 0 movement points. They can move no further.
If your Move into a province uses up your last movement point, one battle is still fought that phase.
Conquering an enemy province slows an army down, counting as 1 province entered for purposes of movement. For example, let's say an army with a speed of 3 enters an enemy province. That army has used up 2/3 of its movement. It can enter one more province that turn, even if it is an enemy province, because the -1 movement deduction is applied after the move is made (an army may wind up with negative movement points only as a result of this rule). A move into a sea province uses up an extra movement point only if there is a battle in the province.
If you conquer a Hero's province, he will probably be more expensive to hire or even non-hireable. Only if the Hero is fairly compatible with your King, will he be likely to forget his defeat and offer his services at a low cost.
If two characters who are controlled by the same King (or, two characters employed by different Kings who are allied with each other) attack the same province in the same action phase, they may fight together in the same battle. If they moved from the same province in making the attack, the chances of uniting for the battle are very good, but if they attacked the province from opposite directions they probably will fight the defenders in separate battles.