The War of the Five Kings begins in blood as House Stark's loyal Sworn Swords clash against House Lannister's heavily armed Regulars. One House Stark's side are numbers and unswerving loyalty in the face of long odds.
Brave, tough, and loyal to a fault, the Sworn Swords will follow the Direwolf banner anywhere their lords might lead. No matter the foe, no matter the odds, the Sworn Swords form the bedrock of House Stark's armies
The great Houses of Westeros had many other, smaller Houses that paid fealty to them. These bonds could be quite strong, reinforced by marriage.
In battle, the goal is to defeat your opponent without being defeated, yourself. If you can attack your enemy and they cannot retaliate, that goes a long way to victory.
Dependable, resilient, and courageous, House Stark's leaders in the War of the Five Kings represent the best the North has to offer. Capable commanders to a man, each hero under the Direwolf banner has trained for a particular place in the line of battle.
Of all the Great Houses of Westeros, there is none more wealthy and ready for war than the Lannisters.
The Lannisters spare no expense when it comes to outfitting their troops. Even the regular line soldier has the finest in arms and armor. So when it comes to a unit as special as their mounted knights, cost is never an issue.
Fielding rank upon rank of Crossbowmen as their primary form of ranged attack would prove prohibitively expensive for any house but Lannister. The advantages are plain.
The lords of House Lannister outfit their troops and allies with the very best arms and armor money can buy, can as such they expect their men to do their duty.
One thing remains true for the unaligned forces in the War of the Five Kings, whether they're fighting for coin, self-interest, or simple survival, they always remain true to themselves. They are a wild card that can be added to any army in the game.