Game of Thrones final season [spoilers]

[Homeless Nutter]

That's beside the point. They needed to set the trench on fire and it looked like they would have completely failed, if the Red Woman hadn't shown up, out of the blue. Bad planning.

Actually it's not .It's actually the point

How so? Care to elaborate?

Jon, Daenerys and their dragons were supposed to stop him. They were waiting for the Nightking to show up, that's why they were not on the battlefield at the start of the battle.

 
Supposed doesn't mean succeeded  

What does that mean? They planned to fail? Are you following what we're talking about, or just giving knee-jerk one-line responses to every post in isolation?

Really? Then why were they lighting their arrows on fire? Seems like a waste of time, since dragon-glass arrow should kill the undead without it. And what do you mean - not everyone had access to dragon-glass? Didn't they go to Dragonstone specifically for that?

Yup they used some fire arrows but that goes to my later point. Consider it's not an easy material to forge with and they limited supply not everyone got a dragon glass weapon . In fact in believe they mention this is episode 2.

Fire is not an easy material to forge? Make up your mind - can you use fire arrows against the wights, or not? If you can - then you don't need obsidian.

Also - since the Dothraki didn't have dragon-glass swords - what were they supposed to accomplish, if Melissandre didn't happen to show up unannounced, literally minutes before the charge, with her - not very useful - fire-sword magic?

Even if you can't kill a wight you can still dismember one and then can still be trampled under horse .

Perhaps, but there are better ways to do it, than to charge head on at an enemy you've never fought in your life and can't see, especially if you have no armor and a short sword as the only weapon. And horses are not immortal. Even if you manage to damage some zombie, but then you immediately die and come back as a zombie - you're not really helping. If the Dothraki waited for the dead to come closer and fight them at the same time as the infantry, chances are they would have lasted longer than half a minute.

What does that matter? Either arrows work against the dead, or not. And clearly fire arrows seem to do the job. So why not shoot at them, while they're standing behind the burning trench?

It matters because theirs a difference between sniping with a bow and valley tactics which are far less effective against such a large hoarde .

When the large horde was standing outside the castle, behind the burning trench, within a the range of arrows, the defenders were not using "valley tactics", were they (did you mean "melee"?)? They were doing nothing, waiting for the enemy to break through. Castle walls and ranged weapons were invented specifically for holding off "large hordes", without being directly in harm's way. Using melee, when you have a castle and the enemy can raise the dead is pretty dumb.