Unfortunatelly i had a bitter experience with this campaign, the first mission was great, well designed, even felt a bit easy but suitable for a first mission, but it still got me excited to play through all of it.
Everything changed on mission 2 however, the first attack wave was not even hard, it was simply unfair, just like how
Jayborino mentioned, the enemy rushes you with way more units than your initial roster, their Dreadguard is like a tier 2 unit compared to your Footmen, they have Aboms while you can't even train knights, their catapults prevents you from building towers to turn that narrow path into a TD corridor, not to mention that one of their units keeps spamming stun on Condor while their rangers completely melts him down.
It's somehow possible to defend against the first wave by sacrificing every unit you have while barely even keeping Condor alive, luring them into your base and turning your peasants into millitia, but then there is the second wave which is just impossible to defend against while you're still rebuilding your base and replenishing lost units. Even if i DID manage to survive the second, third waves, there would absolutely no chance to ever make an offensive comeback with the given limited resources.
If only that Vanndar Stormpike helps me fighting against the undead, i might even have a chance, but no, he just stands still there watching me fight a meter away from him.
I am using classic 1.31.1 since i hate Reforged, so i am quite aware of the insane difficulty spike bug on that version, it happened the very same thing when i played Curse of the Forsaken, one of the missions there was borderline impossible until i found out that the difficult was not intentional, so i had to download 1.30 only so that i could finish that campaign.
Since Lordaeron's Legacy can only be played on 1.31.1, i'm not quite sure how it's even considered to be playable on classic.
Reading some of the comments, i see that there is an even harder mission like the one with the mentione ogres, so maybe it's not even worth it to keep trying at this point.