How to use battering ram

I'm not sure how to use the ram. Do I have to create a formation with s specific kind of unit (melee, archer, horse, or catapult)? I did not see any difference nor any bonus for the ram?.

 

The ram is a support unit. It doesn't do damage itself, it supports other units. Without a battering ram, the walls of a city do not take full damage from an attack. With a battering ram, a non-ranged unit will do full damage to the wall.

 

The battering ram just has to be adjacent to the target city for attacking units to get the benefit. I forget whether ranged/siege benefit from it.

Of course, you probably want the ram to be accompanied by a combat unit so it doesn't get stepped on by an enemy unit.

 

Also of note and to clarify

A ram makes no difference if the city does not have walls
If the city does have walls and you have no ram you only do 17% damage to the walls with horse and infantry
If a ram is adjacent the walls ALL infantry or horse that attacks the city do full damage to the walls.

 

So if I have 1 ram and 6 infantries, they will all do full damage.
If I have a siege tower, is it the same? I tower for all units

 

Yes, mostly, towers bypass walls though

This thread has most likely f my first findings and proof, worth reading from this post on
Catapults
Also this has some great clarifications
City Strength

 

Link the battering ram to a melee unit, rush the city with 3 or 4 ground pounders, hit the city early and often until the walls are reduced to zero. Now the city can't fight back (although individual units sure can). Surround the city until it is besieged and fire away with your ranged units. You should take the city in short order.