Century Games publishes the full combat rules in its own English help centre, and almost none of it reaches the tier-list sites. Everything below is the publisher's text unless we say otherwise.
1. Rows are fixed, and that is why ratio beats power
Infantry are the primary damage takers and sit in the front row. Cavalry are the mobile units in the middle row. Archers deal the highest single-target damage from the back row. Units attack the enemy front row first and only move to the next row once it is cleared. A march with too few Infantry therefore evaporates against one with lower total power — your Archers are exposed the moment the front line breaks. One exception the help centre names explicitly: Cavalry can activate skills that jump straight past the front line and hit Archers in the back row.
2. Rally: nine skills from the leader, four from each member
This is the number that should decide who presses the rally button. The publisher states it plainly — besides the 9 hero skills of the rally initiator, 4 primary hero skills, meaning the first skill of each hero, of rally members are also included. So when you join, an expensive hero contributes barely more than a cheap one with a strong first skill. When you lead, your entire nine-skill set carries the rally, which is why the strongest Governor online should be the one to open it. The help centre says the same thing from the other direction in its Bear Hunt notes: rally damage depends mainly on the captain's heroes and the chance of their skills triggering.
3. Garrison works the same way, with one twist
In a garrison battle the defender with the highest stat bonuses becomes the source of defence bonuses for everyone in the castle, and 4 primary hero skills from the other garrison members are added on top. Reinforcements fill by troop level first and then by type — Infantry, then Cavalry, then Archers.
4. Heroes fire their skills even without matching troops
A stubborn piece of community advice says a hero's skill only works if you bring the matching troop type. The publisher says the opposite: if a squad includes a hero, their expedition skills activate regardless of whether the squad has the matching type of troops, and some are probability-based. It also notes that hero skills work independently of the stats shown in the battle report — which is the usual explanation for a losing march that looked stronger on paper.
5. Where your dead troops go depends on the battle
Casualty handling is not uniform, and this is worth knowing before you rebuild an Infirmary. Attacking another player's Town Center, 35% of the attacker's casualties die outright. In a King's Castle battle, casualties go to the Infirmary until it is full and only then start dying. Infirmary capacity is a real combat stat in Castle fights and nearly irrelevant when you are raiding.
6. Troop tier beats troop count
This one is ours, not the publisher's. Two Governors with identical troop numbers score very differently if one runs a mixed low-tier march and the other is uniform high tier. Converting troops upward moves your Bear Hunt and Viking Vengeance numbers more than training more bodies does. The same logic applies to always attaching heroes to a march — sending troops bare costs you march capacity as well as skills, and in a damage-scored event that is a straight subtraction from your bracket.
Sources: Century Games official English help centre — Combat FAQ, Why does a stronger-looking rally deal less damage?. Section 6 is player-verified behaviour, not publisher text, and is marked as such.