Sanctuary – “Life in death and death in life” [Campaign 4 – Mission 4]

Hmm... 15 weeks have passed. The nearest wolf castle no longer houses 10,000 archers, but "only" 7,000. My army is more than enough to crush them. And that's without the griffins attacking from above and the light creatures that dispel magic.
I think I should play this mission on easy mode. I don't want to wait a year of game time and days of my own. I must have done something wrong....