In Steel Division 2, you have several options for bombing enemy positions. You can call in an air strike from off-map, using artillery observers, or use troops on the map who can mark your targets. Such bombardments have a very large range, causing a large drop in morale in a large area. They can easily stop a large group of infantry attacks and even stop and destroy tanks. A unique advantage of such units is the use of a smoke screen, which is extremely useful in various situations, e.g. during an offensive or retreat.
Pay attention to the caliber of the cannon and the ammunition the unit is equipped with. The bigger, the more devastating the effect and the area of impact. For example, mortars have missiles from 80 to 120 mm, artillery guns from 75 to 150 mm and rocket launchers up to 300 mm! The most powerful artillery units have a truly destructive firepower that can defeat or destroy large enemy units.
There are two subcategories here. Some of the units are regular infantry units equipped with radio. You'll use these troops to target other artillery troops. Fire on selected targets will be more lethal by accelerating the bombardment and firing more accurately.
The second type of troops are artillery observers from off-screen. These are infantry units, cars, trucks or armored vehicles (sometimes armed). They can call in special artillery fire from off the map. They don't require an eye contact with the target, but the number of calls to fire is limited and you have to wait for the targeted area to be bombarded. You can also select several types of bombardment, whether it is a sudden fire, a firewall to be set up in a particular area or a specific place. This is the only type of unit that can call for help from the powerful 380mm rail guns! For this reason they are situation units, because sometimes you will not be able to use them.
Howitzer, SP artillery
They don't need to see the enemy because they can attack any point on the map within their range. These are troops towed by trucks, which you can set up in a designated location on the map. Mobile artillery has the same advantages and disadvantages as howitzers, but it is very mobile and usually has armor. The more experienced the troops, the faster they attack and the more accurate their fire is. Their HE Ammunition is designed to combat "soft" troops - it is extremely strong against such lighter targets and deals large amounts of damage to them.
In addition to their destructive power, they also suppress the morale of enemy units, especially infantry and lightly armored enemy units. A good solution is to put it next to the supply truck to replenish their ammunition stock. Howitzers rarely change location, and these type of trucks can tow such troops. It is worth noting that some guns have a small ammunition stock of AP, but to attack enemy armored units they need to "see" the target. In addition, most artillery units can put up a smoke screen, which is useful when attacking, defending or forcibly retreating.
If you set the target but the enemy disappears from sight, the artillery will still fire a volley to the last known location of the enemy. Also, you can set your own target and order to fire at the desired position. You have to be careful because the bullet flight path is usually well visible and you can easily track the position of your artillery troops (self-damage). Take advantage of that and fire a volley at a suspicious location. In the same way you can get rid of enemy anti-aircraft units, anti-tank guns, etc.
Mortar Team, Mortar SP
It's a lighter variant of the artillery guns. These units are cheaper than ordinary howitzers, have faster fire rate and still have a lot of firepower. Their biggest disadvantage is their small range, which makes them an ineffective unit in later stages of the game, especially on large maps. On the other hand, it's a great support for your army in phase A. Their price and mobility (the mortar team is usually supplied with fast units n battlefield) is very useful in the first minutes of the game. You can defeat enemy troops cheaply and take the initiative at the beginning of the game.
Missile launchers (MLRS)
These are special artillery troops, equipped with powerful missiles. Units in this category have different caliber and size, but all have a powerful effect on the opponent. Even one missile damages many troops over a large area, so this is a very useful skill. Their attacks can be recognized by their bullets, which leave a dense smoky trail of smoke. Also, you can specify the flight path of such missiles and sometimes you can evacuate mobile units from the expected bombing area. On the other hand, it's easy to track the position of such units.
The biggest disadvantage of rocket launchers is their high price and fast ammunition consumption. Usually after only one fire, the unit has no ammunition and must be supported by a supply truck. The biggest advantage is the firepower of these units - for example, accurate katyusha fire can destroy even entire infantry teams, buildings or destroy light and medium tanks. It is a very strong unit, but due to its purpose, it is suitable for situational actions in phases B and C, when you have to attack a heavily fortified forest or a city.