Damage / Critical Damage
A shot may hit or miss a unit. The accuracy depends on distance, range, movement and any modifiers like certain doctrine skills.
Sudden Strike 4 uses two parallel systems based on primary and secondary hit effects. While the primary system mainly affects HP, a secondary hit may trigger critical damage.
Rationale behind the primary hit effect: If the attacking unit’s attack value is higher than the armour value of the target unit, the target takes damage which is subtracted from its HP. If its HP reaches zero, the vehicle is destroyed. Since the armour value is different on each side of the unit, hitting the side or back might give a tactical advantage.
The secondary hit effect triggers critical damage. It allows you to successfully attack more powerful units with less potent units (e.g. destroy the tracks of tanks). The effect of the secondary hit largely depends on the impact as well as the angle of the primary hit.