Even though The main argument is that they are planning a battle to fight for power lords takes other lords lands., They are battling for land because they want to become powerful than anyone because They should stop fighting because it’s wrong and They are not fighting for fun.
Firstly,They battle back then for many lands and did plan to battle in this picture you see they are battling the castle for more power and more vassals they are problaly burned the castles down so they could take4 the land and it maybe had many rich soil.
Secondly, what happend in this picture is that they are using many weapons like crossbows and swords and they had come from