The infantry deals damage to the enemy and also loses a certain number from their army. Only infantry can conquer an enemy province.
Example with no bonuses:
You are attacking 1000 enemy province army with 1001 army. You will win, conquer a province and there will be 1 of your army in it.
When shelling, you inflict damage on the enemy, while you do not lose your army, but you lose cartridges.
Tank deals 5000 damage to the enemy army and reduces the level of the enemy fortress by 2.
Deals certain damage and, with a certain chance, destroy a building in the province (exact values are available in the description of buildings)
Deals 30% damage to the population and army in the enemy province
Destroys all population, army, buildings and make province Undeveloped Land. Also deals damage to the population and armies of neighboring provinces in the amount of 90%.
To use a nuclear weapon, you need to unlock the Nuclear Weapon technology and accumulate 3 uranium