Is there any way to quit the game when in combat mode? It's realy fustrating have to let it all play out which cna take ages when i just wanna turn it off.

Not in the base game, but if you use the HD mod then you can load the game (press L) or finish it quickly (press Q).

https://sites.google.com/site/heroes3hd/eng/description/extended-ui

You can also go to the Main Menu or Load screen from the Combat menu.

CTRL-ALT-DELETE is a more old fashioned way.

Retreating or surrendering can end a combat immediately. Since you're talking about quitting mid-combat, I assume you don't want to save the fight.

Doesn't work though if you're defending a castle with no money nor escape tunnel.

Also, although rare, if either side has brought the Shackles of War to the battle, Retreat/Surrender is disallowed for both parties, regardless of the type of battle.

Both true, though generally rare, I would think. The castle defense is more likely, but in my experience those don't usually take long because one side or the other is badly out matched.

Just slightly annoying.

Started the armageddon's blade quest and it's really hard, Computer just slaughters you within minutes. lol
I completed the previous expansion, seemed more balanced.

How far have you gotten in the campaign?

If you've completed several maps, are you making sure to send each of your heroes that will cary over to the various upgrade points?

First map. I'm sure i got past it on a previous play through.
i can't set the difficulty level on this one, so it's not all that fun.

I completed the previous expatiation, and most of the main game a number of years ago.

There is a way to change difficulty: https://www.youtube.com/watch?v=e_pf1WRj4Jg

Playing on Impossible I found that blitzing was a good strategy on most maps, at least once you have access to higher levels of View Air and View Earth and know where the enemy is located.

That's quite helpful cheers,
might stick them back on to Normal mode :D