Here are general tips for playing the Empire Campaign in Warhammer: Mark of Chaos on HARD Difficulty. A list of all our Warhammer: Mark of Chaos articles can be found here.
We won't be hand-holding you through absolutely everything, but instead just give tips on situations that we found tricky or that you might not have considered.
Chapter 1: The Call of War
Mission 4: Retribution (Erstedorf)
Overall a pretty easy mission, just a lot of running around. It is pretty hard to lose this mission as long as you are not careless and expose your regiments to too much direct combat, since a lot of buildings need to be razed for the mission to be considered a failure.
Having a lot of shooting regiments also helps as time is really not on your side, and melee tends to be a slow grind. Move your entire army around as concentrated fire to destroy each enemy clump is better than trying to protect multiple fronts.
If you lose any models, it is probably because you were not able to move the Captain in front to draw fire, or from the Aspiring Champion's Axe of Doom throw, against which you can't really do anything about.
Remember to grab the banner from the farmland way outside the town proper. It is probably impossible to save those buildings, and even if you did, it would mean you would miss out on the items dropped.