Gain resources, build your own army to lead it into a battle!
Create your own strategy, survive in difficult conditions and then break through enemy's close formation to ruin their castles and reach the sole leadership on the map.
Do not forget about tactics when the fight is on! Good location and right formation will bring you an important victory, which immediately translates into an advantage for the whole war.
Catch your enemies by surprise, until they take a position and build a shield wall, provoke them to mess up the ranks, surround them and destroy completely! Catch up with those who run away and kill them all, because if you do not, they will return back with a sword in a hand!
Alternatively you can use your archers as your main power. While your strong infantry hold back the onslaught in a narrow passageway, a hail of arrows will turn the enemy hordes into heaps of corpses.