Artillery is a revolutionary new feature added to the mod in v4.0. There's currently only field artillery and there are no plans to add siege artillery.
To properly use cannons in battles, you'll need at least:
- Cannon(s) (goods merchant; put into your inventory)
- Cannonballs (weapons merchant; put into your inventory)
- Gunpowder (weapons merchant; put into your inventory)
- Cannoneers (2 per cannon) (taverns)
- Technically you only need one cannoneer per cannon, however there must be enough to man the previous cannon with two before the next one spawns. Ex. If you have 1 cannon then 1 cannoneer can man it, if you have 2 cannons then you must have 3 cannoneers for both to spawn; but both will fire just as quickly and accurately as normal (I think)
Note that while ammo can run out in battle it will not be deleted from your inventory. At least 2-3 sets of cannonballs and gunpowder is recommended per cannon.
Artillery is very expensive and requires a solid financial base. Revolutionary is the way how cannonballs use true ballistics, similar to Napoleonic Warfare.
You can use up to 6 cannons in one battle just equal to your opponent. AI lords use artillery as well, though they are rare. Kings tend to have more cannons. The King of the Rhodoks especially loves artillery. He can bring 6 cannons into one battle if you're unlucky.
Cannons are spawned (as long as you meet the requirements) in a random position either just in front of or just behind the rest of your army. Because of this I would not recommend you rely too heavily on cannons in mountainous areas.
In battle cannoneers will find an eligible opponent to fire at. They'll aim at the ground just before the enemy troops. Cannonballs will always bounce once and land further away, causing terror to all troops between (and more damage). Additionally cannons can shoot at a very tall angle so do not worry too much about placing your troops close in front of them.
Select Artillery group with 4 (not numpad). Use F1 to manually set a target (place a flag on the battlefield) to fire on. Now your cannoneers will shoot at this position. Don't aim on the ground before the enemy troops as cannoneers are perfectly capable to do this themselves. Warband functions such as 'hold fire' and 'charge' can be used to stop/continue shooting. Do this to prevent friendly fire.
Cannoneers are mercenaries and can be upgraded 2x, to 'Experienced Cannoneers' and further to 'Veteran Cannoneers'. They'll load the cannons much faster.
Unfortunately because of how the cannoneers are coded I have noted some issues with following commands when they are not manning a cannon. It is not advised that you bring any more than you need to man your artillery, as they are also quite poor in melee.
You can manually fire cannons. Take control by interacting with the cannon (aim at the barrel and hold down F to manually fire it) . Beware you cannot undo this. Use arrow keys to aim (set angle) the cannon barrel and load it. Interact with the cannon (press F) again to fire it.
I have also found this function to be quite buggy, so I would not recommend relying on this method of using cannons.
You can adjust the settings for artillery at the camp menu -> options. You can completely disable artillery or adjust the spawn rate.