The Hobbit: Kingdoms of Middle-earth is built around attacking other kingdoms, and defending your kingdom against attacks from others. Attacking and defending are a function of not only what troops you have, but also having the right types of troops, and having a smart battle plan which is derived from scouting other kingdoms. In addition, you can also attack goblin camps, which are computer controlled lairs. If you do it right, you can get a whole lot of resources and increase your rating in the game, but if you do it wrong, you can end up losing all of your troops and having to start over again from scratch.
There are four types of troops in the game. If you play as the dwarves, you have foot troops, which consist of dwarven militia, dwarf warriors and battering rams. You have mounted troops, which consist of mounted dwarves, boar riders and heavy boar riders. You also have ranged troops, which consist of axe throwers, siege crossbows and catapults.
If you play as the elves, then your foot troops will be elven militia, elven warriors and battering rams. Your mounted troops will be mounted elves, mounted hunters and mounted galahadrim. Your ranged troops will be elven archers, scorpions and ents. Both races will have three supply troop types: the porters, supply carts and supply wagons.
Attacking works in a rock paper scissors style of play. Foot troops are beaten by ranged troops, but are strong against mounted troops, Mounted troops are strong against ranged troops but weak against foot troops. Range troops are strong against foot troops but weak against mounted troops. Supply troops aren’t strong or weak against anybody, although in general, they are unable to defend themselves, so you will need to send in attack troops to defend them.
Supply troops are kept in the city walls, and they, like the attack troops, will have a “type” that they are strong or weak against when they get attacked. Traps are strong against foot troops and beaten by mounted troops. Caltrops are strong against mounted troops but weak against ranged troops. Defense crossbows and defensive trebuchets are strong against ranged troops but weak against foot troops.