First, I send out scouts for reconnaissance, then I see what's around the castle (whether there are any hidden resources or buildings that generate income). Then, using a chain and passing of elves, everything works out...
In principle, I don't go into swamps, but if it's the first few days, it can work as a secondary strategy...
I don't understand why you took dwarves with you; they only slow you down. I have everyone running around on knights. And you can beat mummies, especially when playing as Ivorn....
Personally, I've found a small improvement: with 10 grand knights and 40 knights (which is about 70% of standard games), I can easily take a dwarf castle at level 75 with a grade stack, with minimal losses. Thanks for your attention...