Doctrines are a form of tree of talents that you can customize as much as you want, before the mission, using stars. You gain skill points for your resu.ts during missions. You can obtain a maximum of 3 stars.
It is difficult to determine what actually affects the number of stars you receive. Sometimes, what you need is high score for the enemies you destroy, obtain decorations for tactical approach (flanking the enemy, capturing of equipment healing severely wounded units, etc.) or attack the enemy in a specific way (e.g. by constructing floating bridges or by capturing abandoned enemy tanks).
In some missions, depending on the doctrine you pick, you can receive additional units. Sometimes, this will be a tank, artillery or an infantry unit. For example, in the 4th mission of the Soviet campaign, if you pick support doctrine, you will receive a SU-122 artillery vehicle (1), for armored doctrine T43/76 (2), for infantry doctrine, you will receive 9 soldiers, instead of a vehicle (3). It is a good idea to play a mission several times to find out which doctrine works best for you.
Usually, you will have to play a mission once, to decide which doctrine works best for you, given the specific scenario. Mission description does not provide any information on type of army you, or the enemy, will have. Each doctrine has some base skills that cannot be disabled (some of them are exclusive). Some of the skills are the same for different doctrines, although they differ in price. Before each mission, you can freely choose skills, but only from one doctrine. You do not have to pick them in any specific order (you can pick a skill for 5 stars and a skill for 1 star, or a single skill for 1,2 and 3 stars, assuming that you have 7 points).
These are some of the skills that are present in more than one doctrine in each of the factions:
- Hand grenades (light infantry are armed with fragmentation grenades; effective against infantry).
- Piggybacking (you can transport up to 4 passengers in any tank; useful for transportation).
- Hatch lookout (if there is room for a commander in a tank, he can open the hatch and observe the area from the turret; this way, you will increase range of vision of the tank, but the commander is exposed and vulnerable to fire).
- Smoke grenades (infantry can throw smoke grenades that form fog of war; useful for both attack and retreat).
- Demolition kits (some infantry types are deployed with additional gear, e.g. mines, AT grenades or dynamite; available only for infantry and only for the German support doctrine)
- Sandbag cover (tanks, some armored vehicles and cannons can be fortified with sandbags; this reduces damage taken to the sides and to the front of the vehicle, but after losing all the sandbags, the unit loses this skill).