campaign finished

[persoiranian]

am i too weak in this game or this battle is impossible? i tried every single tactic i could think about!!! killing the enemy's leader is not effective and using swamps to slow down the enemy or even the forest roads didn't help me. i tried to move my army to the other side of the bridge in south and defend my position there,but before my troops could reach there, the enemy cavalry attacked my forces, i tried to fight back by my cavalry and it was effective but due to heavy casualities, my army was so weak to defeat the enemy.