@Reimos sure there are examples of long ass wars. but look at when? they all old. do you know why? i not sure either, lol, but i can guess that it has to do with how fully one could destroy another. since 'the bomb' dropped, the world has adopted a tendency of doing it dirty and fast or not doing it at all. so i considered the level of tech they have, enough for bombs with some magic based stuff. they can destroy a lot using mana, so how can two sides not destroy each other in the long run? also is the other side really so equal to the original rulers that they can keep going fighting for such long time? is the original ruler that weak that they can't completely destroy the enemy so the dirty news is hidden 'forever'? there can be explanations, sure, but i don't think we will dive that deep. so we will have to accept what it is for what it is, but that doesn't change the impression it gave me.
so yeah, wars in the past took long because of limitations, they literally couldn't kill the bastards they hated. considering this, i could only come to the conclusion that they don't really want to destroy one another and the war should be quite superficial (maybe even beneficial for both parties), or both sides are incompetent (what we see a lot on fantasy).
we will have to wait and see if the author will give any more explanation, i wouldn't bet on it tho, i would rather bet on mc cleaning the floor with both sides and be done with it.